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  • 1351.
    Yushmanov, Pavel V.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Stilbs, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Stopped-flow F-19 NMR studies of surfactant precipitation2006In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 291, no 1-3, p. 59-62Article in journal (Refereed)
    Abstract [en]

    The kinetics of the phase change in surfactant solutions is studied by F-19 stopped-flow NMR. In the aqueous solution of sodium perfluooctanoate, we observe precipitation and crystal growth induced by the addition of NaCl solution to the system. The time dependences of the NMR signal intensity and chemical shift, evaluated in the framework of a single model, narrow the range of possible scenarios, the most plausible of which is monomer incorporation into the growing crystals. In accordance to existing models of crystallization, both the nucleation rates and the crystal growth rates are strongly dependent on the magnitude of supersaturation.

  • 1352. Zahedinejad, M.
    et al.
    Fulara, H.
    Khymyn, R.
    Houshang, A.
    Dvornik, M.
    Fukami, S.
    Kanai, S.
    Ohno, H.
    Åkerman, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. Physics Department, University of Gothenburg, Gothenburg, Sweden NanOsc AB, Kista, Sweden.
    Memristive control of mutual spin Hall nano-oscillator synchronization for neuromorphic computing2022In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 21, no 1, p. 81-87Article in journal (Refereed)
    Abstract [en]

    Synchronization of large spin Hall nano-oscillator (SHNO) arrays is an appealing approach toward ultrafast non-conventional computing. However, interfacing to the array, tuning its individual oscillators and providing built-in memory units remain substantial challenges. Here, we address these challenges using memristive gating of W/CoFeB/MgO/AlOx-based SHNOs. In its high resistance state, the memristor modulates the perpendicular magnetic anisotropy at the CoFeB/MgO interface by the applied electric field. In its low resistance state the memristor adds or subtracts current to the SHNO drive. Both electric field and current control affect the SHNO auto-oscillation mode and frequency, allowing us to reversibly turn on/off mutual synchronization in chains of four SHNOs. We also demonstrate that two individually controlled memristors can be used to tune a four-SHNO chain into differently synchronized states. Memristor gating is therefore an efficient approach to input, tune and store the state of SHNO arrays for non-conventional computing models.

  • 1353.
    Zalesny, Robert
    et al.
    Wroclaw Univ Sci & Technol, Fac Chem, Dept Phys & Quantum Chem, Wybrzeze Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Alam, Md Mehboob
    Indian Inst Technol Bhilai, Dept Chem, Raipur 492015, Chhattisgarh, India..
    Day, Paul N.
    Air Force Res Lab, Dayton, OH 45433 USA..
    Nguyen, Kiet A.
    Air Force Res Lab, Dayton, OH 45433 USA..
    Pachter, Ruth
    Air Force Res Lab, Dayton, OH 45433 USA..
    Lim, Chang-Keun
    Univ Buffalo State Univ New York, Inst Lasers Photon & Biophoton, Dept Chem, Buffalo, NY 14260 USA.;Nazarbayev Univ, Dept Chem & Mat Engn, Sch Engn & Digital Sci, Nur Sultan City 010000, Kazakhstan..
    Prasad, Paras N.
    Univ Buffalo State Univ New York, Inst Lasers Photon & Biophoton, Dept Chem, Buffalo, NY 14260 USA..
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Computational design of two-photon active organic molecules for infrared responsive materials2020In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 8, no 29, p. 9867-9873Article in journal (Refereed)
    Abstract [en]

    In this study we report theoretical studies of the linear and nonlinear optical properties of a series of pi-conjugated organic cations and their neutral precursors which show pi-stacking to exhibit aggregation-enhanced optical properties. These organic cations show promise as photoactive layers in hybrid quasi-2D perovskites for applications in optoelectronics, particularly in the short wavelength infrared region. We analyze the one- and two-photon (2P) absorption (2PA) transition strengths of several excited states in the considered systems at the coupled-cluster level theory employing the CC2 model. Furthermore, a microscopic insight into their 2P activity has been obtained using the generalized few-state model (GFSM). Based on our GFSM results, we pinpoint the origin of the desired nonlinear optical properties and provide a design strategy for efficient IR photoactive organic materials with potential application in organic-inorganic hybrid quasi-2D perovskites.

  • 1354.
    Zali, Amir
    et al.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran 111554563, Iran..
    Kashani-Bozorg, Seyed Farshid
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran 111554563, Iran..
    Lalegani, Zahra
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran 111554563, Iran..
    Hamawandi, Bejan
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fabrication of TiFe-Based Electrodes Using High-Energy Ball Mill with Mn Additive for NiMH Batteries2022In: BATTERIES-BASEL, ISSN 2313-0105, Vol. 8, no 10, p. 182-, article id 182Article in journal (Refereed)
    Abstract [en]

    Binary and ternary (with the addition of Mn) TiFe-based intermetallic compound powders were fabricated by high energy ball milling, and their electrochemical behavior as negative electrodes was investigated in 6M-KOH. X-ray diffraction exhibited the single phase of nanostructured binary and ternary TiFe-based crystallites after 20 h of milling followed the amorphous phase formation. Addition of Mn increased peak broadening and in turn decreased the nanocrystallite size of TiFe. Electrode properties of 20, 40, 60, and 70 h binary milled products showed that the discharge capacity of the 60 h one offered a maximum discharge capacity of similar to 169 mAhg(-1). Although substitution of Mn for Ti (TixFeMnx,( )x = 0.1, 0.2) caused a decrease in initial discharge capacity, the periodic stability increased compared to the binary TiFe and ternary TiFe1-xMnx (x = 0.1, 0.2). The ternary Ti0.9FeMn0.1 electrode maintained similar to 53% of its initial discharge capacity after five cycles of charge-discharge; this was just 28% in the case of binary TiFe electrode.

  • 1355. Zambrano, Noelia
    et al.
    Tyrode, Eric
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Mira, Isabel
    Marquez, Laura
    Rodriguez, Maria-Patricia
    Salager, Jean-Louis
    Emulsion Catastrophic Inversion from Abnormal to Normal Morphology. 1. Effect of the Water-to-Oil Ratio Rate of Change on the Dynamic Inversion Frontier2003In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 42, no 1, p. 50-56Article in journal (Refereed)
    Abstract [en]

    The rate of addn. of the internal phase affects the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphol. At a low addn. rate, the inversion takes place after a small amt. of the internal phase is added, and it happens through the occurrence of multiple emulsion morphol. At a high addn. rate, the inversion appears to be delayed, and it takes place without the occurrence of a multiple emulsion. [on SciFinder (R)]

  • 1356.
    Zander, Thomas
    et al.
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Wieland, D. C. Florian
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Raj, Akanksha
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Salmen, Paul
    TU Dortmund, DELTA, Fak Phys, D-44221 Dortmund, Germany..
    Dogan, Susanne
    TU Dortmund, DELTA, Fak Phys, D-44221 Dortmund, Germany..
    Dédinaité, Andra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Garamus, Vasil M.
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Schreyer, Andreas
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Willumeit-Roemer, Regine
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Influence of high hydrostatic pressure on solid supported DPPC bilayers with hyaluronan in the presence of Ca2+ ions2019In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 36, p. 7295-7304Article in journal (Refereed)
    Abstract [en]

    The molecular mechanisms responsible for outstanding lubrication of natural systems, like articular joints, have been the focus of scientific research for several decades. One essential aspect is the lubrication under pressure, where it is important to understand how the lubricating entities adapt under dynamic working conditions in order to fulfill their function. We made a structural investigation of a model system consisting of two of the molecules present at the cartilage interface, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and hyaluronan, at high hydrostatic pressure. Phospholipid layers are found at the cartilage surfaces and are able to considerably reduce friction. Their behavior under load and varied solution conditions is important as pressures of 180 bar are encountered during daily life activities. We focus on how divalent ions, like Ca2+, affect the interaction between DPPC and hyaluronan, as other investigations have indicated that calcium ions influence their interaction. It could be shown that already low amounts of Ca2+ strongly influence the interaction of hyaluronan with DPPC. Our results suggest that the calcium ions increase the amount of adsorbed hyaluronan indicating an increased electrostatic interaction. Most importantly, we observe a modification of the DPPC phase diagram as hyaluronan absorbs to the bilayer which results in an L-alpha-like structure at low temperatures and a decoupling of the leaflets forming an asymmetric bilayer structure.

  • 1357. Zander, Thomas
    et al.
    Wieland, D. C. Florian
    Raj, Akanksha
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wang, Min
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nowak, Benedikt
    Krywka, Christina
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. SP Tech Res Inst Sweden.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden.
    Garamus, Vasil M.
    Schreyer, Andreas
    Willumeit-Romer, Regine
    The influence of hyaluronan on the structure of a DPPC-bilayer under high pressures2016In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 142, p. 230-238Article in journal (Refereed)
    Abstract [en]

    The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2 kbar (200 MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.

  • 1358.
    Zelenin, Sergey
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Käller, M.
    Nazarov, A.
    Brismar, H.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    High density custom microarrays formed by microcompartment amplification on glass surface2014In: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014, Chemical and Biological Microsystems Society , 2014, p. 1027-1029Conference paper (Refereed)
    Abstract [en]

    Compartmentalization of a single DNA molecule is necessary for digital amplification. In the present study we have developed a microscale isothermal amplification using exponential rolling circle amplification (RCA). RCA was performed in PDMS microcompartments on a microarray glass, with a volume of less than 1 pL. Resulting amplicons were attached to the glass surface and formed a custom array with the density of spots above 2,5 × 105 per cm2. Our technology can be applied for digital amplification of DNA or RNA from a variety of complex biological samples in a microchip format.

  • 1359.
    Zeng, Lai
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Transport Phenomena. KTH Royal Inst Technol, Dept Chem Engn, Tekn Ringen 42, SE-10044 Stockholm, Sweden..
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Transport Phenomena.
    Solubility of Two Polymorphs of Tolbutamide in n-Propanol: Comparison of Methods2020In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 109, no 10, p. 3021-3026Article in journal (Refereed)
    Abstract [en]

    The solid-liquid solubility of two polymorphs of the title compound has been measured in n-propanol over the temperature range (278 K-303 K) by an isothermal, gravimetric method and a low heating rate polythermal method. Due to marked differences in the settling behavior of crystals of the two polymorphs in the investigated solvent, it is found that the low heating rate polythermal method gives the overall best performance for this particular system. Systematic slurry conversion experiments show that FII is the stable polymorph over the investigated temperature range (268 K-308 K). Solubility data for both polymorphs is well correlated, and has been extrapolated to the melting point, by a previously proposed semi-empirical regression model based on solid-phase calorimetric data. The system exhibits a marked positive deviation from Raoult's law, with solute activity coefficients at equilibrium decreasing with increasing temperature.

  • 1360.
    Zhang, Chu
    et al.
    Lund Univ, Synchrotron Radiat Res, Box 118, S-22100 Lund, Sweden..
    Wang, Baochang
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden..
    Hellman, Anders
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden..
    Shipilin, Mikhail
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Schaefer, Andreas
    Merte, Lindsay R.
    Malmö Univ, Mat Sci & Appl Math, S-20506 Malmö, Sweden..
    Blomberg, Sara
    Lund Univ, Dept Chem Engn, Box 124, S-22100 Lund, Sweden..
    Wang, Xueting
    Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Competence Ctr Catalysis, S-41296 Gothenburg, Sweden..
    Carlsson, Per-Anders
    Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Competence Ctr Catalysis, S-41296 Gothenburg, Sweden..
    Lundgren, Edvin
    Lund Univ, Synchrotron Radiat Res, Box 118, S-22100 Lund, Sweden..
    Weissenrieder, Jonas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Resta, Andrea
    Synchrotron SOLEIL, St Aubin, State Two, France..
    Mikkelsen, Anders
    Lund Univ, Synchrotron Radiat Res, Box 118, S-22100 Lund, Sweden..
    Andersen, Jesper N.
    Lund Univ, Synchrotron Radiat Res, Box 118, S-22100 Lund, Sweden..
    Gustafson, Johan
    Lund Univ, Synchrotron Radiat Res, Box 118, S-22100 Lund, Sweden..
    Steps and catalytic reactions: CO oxidation with preadsorbed O on Rh(553)2022In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 715, article id 121928Article in journal (Refereed)
    Abstract [en]

    Industrial catalysts are often comprised of nanoparticles supported on high-surface-area oxides, in order to maximise the catalytically active surface area and thereby utilise the active material better. These nanoparticles expose steps and corners that, due to low coordination to neighboring atoms, are more reactive and, as a consequence, are often assumed to have higher catalytic activity. We have investigated the reaction between CO and preadsorbed O on a stepped Rh(553) surface, and show that CO oxidation indeed occurs faster than on the flat Rh(111) surface at the same temperature. However, we do find that this is not a result of reactions at the step sites but rather at the terrace sites close to the steps, due to in-plane relaxation enabled by the step. This insight can provide ways to optimize the shape of the nanoparticles to further improve the activity of certain reactions.

  • 1361.
    Zhang, Chuanhui
    et al.
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Liu, Min
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Jin, Ying
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Sun, Dongbai
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    The corrosive influence of chloride ions preference adsorption on α-Al2O3(0001) surface2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 347, p. 386-391Article in journal (Refereed)
    Abstract [en]

    Conductor-like screening model (COSMO), Periodic DFT calculations have been performed on a Al2O3 surface to model the influence of preference adsorption and interaction of chloride ions at increasing monolayer coverage on undefective passive film on Aluminum in solution environment. The results evidence that the critical monolayer of Cl- is 3/7, which is redefined. With increasing Cl- adsorption, both the first and second Cl- move from Al(1) atop and bridge10 sites to O(5) sites, suggesting that the weaker interaction between Cl- and Al2O3 surface but stronger interactions between three ions make the electrons uniformly occupy on the energy levels of them. More calculations shows that the preference adsorption sites of Cl- are independent of the surface area of oxide, and the adsorption energy decrease in three steps, each adsorption energy step only relate to the adsorption site and the morphology. On undefective oxide film, low coverage Cl- adsorption would restrain surface breakdown to happen which is consistent with the experiment results.

  • 1362.
    Zhang, Fan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Electrochemical and AFM studies of mussel adhesive protein (Mefp-1) as corrosion inhibitor for carbon steel2011In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, no 3, p. 1636-1645Article in journal (Refereed)
    Abstract [en]

    Adsorption of mussel adhesive protein (Mefp-1) derived from the marine mussel Mytilus edulis and its corrosion inhibition for carbon steel were studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in NaCl solutions at 01 4.6. The results indicate that the Mefp-1 confers significant corrosion inhibition of carbon steel, and the chloride concentration of the solution has an influence on the inhibition efficiency. Within a short exposure time, the inhibition efficiency is higher in the solution with a higher chloride concentration, whereas, for longer exposure time, up to one week, higher inhibition efficiency was obtained in the solution with a lower chloride concentration. AFM imaging was used both ex situ and in situ to investigate Mefp-1 adsorption. The in situ AFM measurements enable the protein adsorption on carbon steel to be visualized in real time in the solution. The AFM images illustrate how the Mefp-1 layer is formed on carbon steel. Measurements using bovine serum albumin (BSA) were also performed for comparison. The results showed that BSA also confers significant corrosion inhibition of carbon steel even though the BSA film formation process is slightly different from that of Mefp-1.

  • 1363.
    Zhang, Feng
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ai, Yue-Jie
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Fang, Wei-Hai
    Nonadiabatic histidine dissociation of hexacoordinate heme in neuroglobin protein2010In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215Article in journal (Refereed)
    Abstract [en]

    In the present work, density functional theory and canonical nonadiabatic Monte Carlo transition state theory have been used to investigate histidine dissociation process from the hexacoordinate heme in Ngb protein. The potential energy surfaces (PES) of the lowest singlet, triplet, and quintet states are calculated by stepwise optimization along with the histidine dissociation pathway. Based on the calculated two-dimensional PES, the histidine dissociation rates for the spin-forbidden processes via singlet to triplet and singlet to quintet transitions have been calculated by the nonadiabatic Monte Carlo transition state theory in canonical ensemble. The present study provides a quantitative description on spin-forbidden histidine dissociation processes.

  • 1364.
    Zhang, Igor Ying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Wu, Jianming
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Xu, Xin
    Trends in R-X Bond Dissociation Energies (R-center dot = Me, Et, i-Pr, t-Bu, X-center dot = H, Me, Cl, OH)2010In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 6, no 5, p. 1462-1469Article in journal (Refereed)
    Abstract [en]

    Trends for R X bond dissociation energies have been examined with density functional methods of B3LYP, BMK, M06-2X, MC3MPW, B2PLYP, MCG3-MPW, and XYG3, as well as 03, MCG3/3, G3X, and 04 theories as functions of alkylation (i.e., IT = Me, Et, i-Pr, (-Bu) and X' substitution (i.e., X' = H, Me, Cl, OH). The results highlight the physical origin of success or failure of each method and demonstrate the good agreement with experimental results for G4, MCG3-MPW, and XYG3. The last holds great promise as a reliable method that is applicable to larger systems.

  • 1365. Zhang, J.
    et al.
    Liu, Y.
    Sha, G.
    Jin, S.
    Hou, Ziyong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing, China.
    Bayat, M.
    Yang, N.
    Tan, Q.
    Yin, Y.
    Liu, S.
    Hattel, J. H.
    Dargusch, M.
    Huang, X.
    Zhang, M. -X
    Designing against phase and property heterogeneities in additively manufactured titanium alloys2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 4660Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) creates digitally designed parts by successive addition of material. However, owing to intrinsic thermal cycling, metallic parts produced by AM almost inevitably suffer from spatially dependent heterogeneities in phases and mechanical properties, which may cause unpredictable service failures. Here, we demonstrate a synergistic alloy design approach to overcome this issue in titanium alloys manufactured by laser powder bed fusion. The key to our approach is in-situ alloying of Ti−6Al−4V (in weight per cent) with combined additions of pure titanium powders and iron oxide (Fe2O3) nanoparticles. This not only enables in-situ elimination of phase heterogeneity through diluting V concentration whilst introducing small amounts of Fe, but also compensates for the strength loss via oxygen solute strengthening. Our alloys achieve spatially uniform microstructures and mechanical properties which are superior to those of Ti−6Al−4V. This study may help to guide the design of other alloys, which not only overcomes the challenge inherent to the AM processes, but also takes advantage of the alloy design opportunities offered by AM.

  • 1366.
    Zhang, Li
    et al.
    Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yang, Xichuan
    Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Cai, Bin
    Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Wang, Haoxin
    Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yu, Ze
    Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Triazatruxene-based sensitizers for highly efficient solid-state dye-sensitized solar cells2020In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 212, p. 1-5Article in journal (Refereed)
    Abstract [en]

    Molecularly engineered strongly conjugated and rigid hybrid triazatruxene (TAT)-based dyes ZL001 and ZL003 were fabricated as excellent dyes for solid-state dye sensitized solar cells (ssDSSC). Y123 was used as a reference dye. The efficiencies of 5.4%, 6.6% and 6.1% for ZL001, ZL003 and Y123 based solid-state devices are obtained, respectively, with 2,2',7,7'-tetrakis (N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) as hole transporting material. The photovoltaic performance of the TAT-based dye ZL003 was higher than previously published Y123 dye, which possesses a strong push pull conjugated structure. The effects of molecular structure on optical and electrochemical properties, charge extraction kinetics, and photovoltaic performance of the sensitizers were systematically researched. Our results indicate that TAT-based dyes are attractive for application in ssDSSC.

  • 1367.
    Zhang, Li
    et al.
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yang, Xichuan
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Li, Shuping
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yu, Ze
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China.;KTH Royal Inst Technol, Dept Chem, SE-10044 Stockholm, Sweden..
    Electron-Withdrawing Anchor Group of Sensitizer for Dye-Sensitized Solar Cells, Cyanoacrylic Acid, or Benzoic Acid?2020In: Solar RRL, E-ISSN 2367-198X, Vol. 4, no 3, article id 1900436Article in journal (Refereed)
    Abstract [en]

    High electron-injection efficiency is important for further development of dye-sensitized solar cells (DSSCs). Different electron acceptors have different electron-injection capabilities, which affect device performance. Herein, the effects of two organic triazatruxene (TAT)-based donor-pi-bridge-acceptor sensitizers applied in DSSCs are reported. The sensitizers have either rigid 4-ethynyl benzoic acid (EBA) or Z-type cyanoacrylic acid (CA) as their electron acceptor, denoted as ZL003 and ZL005, respectively. Time-resolved photoluminescence (TR-PL) spectroscopy is applied to reveal the electron transfer dynamics between the sensitizers and TiO2 films. Notably, ZL003 has higher electron-injection efficiency compared with that of ZL005, which is consistent with the higher efficiency and photocurrent of devices based on the former. The dye loading of ZL003 is nearly twice as great as that of ZL005, which accounts for the lower photocurrent of the device. The charge recombination lifetimes for the two dyes are consistent with their open-circuit voltage. Consequently, the ZL003-based devices achieve a higher power conversion efficiency of 13.4% compared with only 7.2% for ZL005.

  • 1368. Zhang, P.
    et al.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Dalian Univ Technol.
    Electrocatalytic Hydrogenation and Oxidation in Aqueous Conditions(dagger)2020In: Chinese journal of chemistry, ISSN 1001-604X, E-ISSN 1614-7065, Vol. 38, no 9, p. 996-1004Article in journal (Refereed)
    Abstract [en]

    Water molecule contains one oxygen and two hydrogen atoms, making it a potential oxygen and hydrogen source. Electrocatalytic organic reduction and oxidation using water as oxygen and/or hydrogen donors provide an environmentally friendly and sustainable strategy to replace traditional chemical-driven stoichiometric reactions that use sacrificial reagents. Furthermore, the development of electrochemical synthesis provides a potential application for low tension photoelectricity, which is not cost-effective during boosted voltage and application. In the last decade, electrocatalytic redox reactions of organic molecules in aqueous media had shown progress owing to the development of electrode materials and water-splitting technology. This paper highlights several electrocatalytic systems and corresponding mechanisms for both hydrogenation and oxidative transformation of representative compounds. The activation process of protons and water on the working electrode surface has received special focus. Furthermore, paired electrolysis using water as the oxygen and hydrogen source has been demonstrated. This paired system combines hydrogenation and oxidation half-reactions in one cell using water as the hydrogen and oxygen source, resulting in high atomic and electron utilization rates.

  • 1369.
    Zhang, Qiong
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Tu, Yaoquan
    Tian, He
    Zhao, Yan-Li
    Stoddart, J. Fraser
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Working Mechanism for a Redox Switchable Molecular Machine Based on Cyclodextrin: A Free Energy Profile Approach2010In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 19, p. 6561-6566Article in journal (Refereed)
    Abstract [en]

    This paper reports the working mechanism for a redox-responsive bistable [2]rotaxane incorporating an alpha-cyclodextrin (alpha-CD) ring (J. Am. Chem. Soc. 2008, 130, 11294-11296), based on free energy profiles obtained from all-atom molecular dynamics simulations. Employing an umbrella sampling technique, the free energy profiles (potential of mean force, PMF) were calculated for the shuttling motion of the alpha-CD ring between a tetrathiafulvalene (TTF) recognition site and a triazole (TZ) unit on the dumbbell of the rotaxane for three oxidation states (0, +1, +2) of the TTF unit. These calculated free energy profiles verified the experimentally observed binding preference for each state. Analysis of the free energy components reveals that, for these alpha-CD-based rotaxanes with charged TTF units, the real driving force for the shuttling in the oxidized states is actually the interactions between water and the rotaxane components, which overwhelms the attractive interactions between the alpha-CD ring and the charged dumbbell. In this work, we put forward a feasible approach to correctly describe the complexation behavior of CD with charged species, that is, free energy profiles obtained from all-atom molecular dynamics simulation.

  • 1370.
    Zhang, Teng
    et al.
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Wang, Tingting
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Grazioli, Cesare
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Guarnaccio, Ambra
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy.;ISM CNR, Ist Struttura Mat, I-34149 Trieste, Ts, Italy..
    Brumboiu, Iulia Emilia
    Pohang Univ Sci & Technol POSTECH, Dept Chem, Pohang 37673, South Korea..
    Johansson, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics. Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, Box 516, SE-75120 Uppsala, Sweden.;Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, F-75005 Paris, France..
    Beranova, Klara
    Elettra Sincrotrone Trieste SCpA, Str Statale 14,Km 163-5, I-34149 Trieste, Italy.;Czech Acad Sci, FZU Inst Phys, Prague 18221, Czech Republic..
    Coreno, Marcello
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy.;ISM CNR, Ist Struttura Mat, I-34149 Trieste, Ts, Italy..
    de Simone, Monica
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Brena, Barbara
    Uppsala Univ, Dept Phys & Astron, Div Mat Theory, Box 516, SE-75120 Uppsala, Sweden..
    Liu, Liwei
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Wang, Yeliang
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Puglia, Carla
    Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, Box 516, SE-75120 Uppsala, Sweden..
    Evidence of hybridization states at the donor/acceptor interface: case of m-MTDATA/PPT2022In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 34, no 21, p. 214008-, article id 214008Article in journal (Refereed)
    Abstract [en]

    We performed a spectroscopic study on the m-MTDATA (donor) and PPT (acceptor) molecular vertical heterostructure. The electronic properties of the donor/acceptor interface have been comprehensively characterized by synchrotron radiation-based photoelectron spectroscopy and near-edge x-ray absorption fine structure. The spectroscopic results reveal the existence of new hybridization states in the original molecular energy gap, likely attributed to the interaction between the donor and the acceptor molecules at the interface. Such hybridized states can have a significant impact on the charge transport in organic electronic devices based on donor-acceptor molecules and can explain the increased efficiency of device using such molecules.

  • 1371.
    Zhang, Wei
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Hua, Yong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Wang, Linqin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zhang, Biaobiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Liu, Peng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Leandri, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Guo, Yu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Chen, Hong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Dalian Univ Technol DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Kloo, Lars
    The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells2019In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 9, p. 6768-6779Article in journal (Refereed)
    Abstract [en]

    Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.

  • 1372.
    Zhang, Xiaoliang
    et al.
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Cappel, Ute B.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Jia, Donglin
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Zhou, Qisen
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Du, Juan
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Sloboda, Tamara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Svanström, Sebastian
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Johansson, Fredrik O. L.
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Lindblad, Andreas
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Liu, Jianhua
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Rensmo, Håkan
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala Univ, Phys Chem, Dept Chem Angstrom, S-75120 Uppsala, Sweden..
    Probing and Controlling Surface Passivation of PbS Quantum Dot Solid for Improved Performance of Infrared Absorbing Solar Cells2019In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 11, p. 4081-4091Article in journal (Refereed)
    Abstract [en]

    Surface properties of colloidal quantum dots (CQDs) are critical for the transportation and recombination of the photoinduced charge carrier in CQD solar cells, therefore dominating the photovoltaic performance. Herein, PbS CQD passivated using liquid-state ligand exchange (LSLX) and solid-state ligand exchange (SSLX) strategies are in detail investigated using photoelectron spectroscopy (PES), and solar cell devices are prepared to understand the link between the CQD surface properties and the solar cell function. PES using different energies in the soft and hard Xray regime is applied to study the surface and bulk properties of the CQDs, and the results show more effective surface passivation of the CQDs prepared with the LSLX strategy and less formation of lead-oxide. The CQD solar cells prepared with LSLX strategy show higher performance, and the photoelectric measurements suggest that the recombination of photoinduced charges is reduced for the solar cell prepared with the LSLX approach. Meanwhile, the fabricated solar cells exhibit good stability. This work provides important insights into how to fine-tune the CQD surface properties by improving the CQD passivation, and how this is linked to further improvements of the device photovoltaic performance.

  • 1373. Zhang, Y.
    et al.
    Ran, L.
    Li, Z.
    Zhai, P.
    Zhang, B.
    Fan, Z.
    Wang, C.
    Zhang, X.
    Hou, J.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Center of Artificial Photosynthesis for Solar Fuels, School of Science, Westlake University, Hangzhou, 310024, China.
    Simultaneously Efficient Solar Light Harvesting and Charge Transfer of Hollow Octahedral Cu2S/CdS p–n Heterostructures for Remarkable Photocatalytic Hydrogen Generation2021In: Transactions of Tianjin University, ISSN 1006-4982, Vol. 27, no 4, p. 348-357Article in journal (Refereed)
    Abstract [en]

    Solar-driven water splitting is a promising alternative to industrial hydrogen production. This study reports an elaborate design and synthesis of the integration of cadmium sulfide (CdS) quantum dots and cuprous sulfide (Cu2S) nanosheets as three-dimensional (3D) hollow octahedral Cu2S/CdS p–n heterostructured architectures by a versatile template and one-pot sulfidation strategy. 3D hierarchical hollow nanostructures can strengthen multiple reflections of solar light and provide a large specific surface area and abundant reaction sites for photocatalytic water splitting. Owing to the construction of the p–n heterostructure as an ideal catalytic model with highly matched band alignment at Cu2S/CdS interfaces, the emerging internal electric field can facilitate the space separation and transfer of photoexcited charges between CdS and Cu2S and also enhance charge dynamics and prolong charge lifetimes. Notably, the unique hollow Cu2S/CdS architectures deliver a largely enhanced visible-light-driven hydrogen generation rate of 4.76 mmol/(g·h), which is nearly 8.5 and 476 times larger than that of pristine CdS and Cu2S catalysts, respectively. This work not only paves the way for the rational design and fabrication of hollow photocatalysts but also clarifies the crucial role of unique heterostructure in photocatalysis for solar energy conversion. 

  • 1374.
    Zhang, Yunxiao
    et al.
    Univ Western Australia, Sch Mol Sci, Perth, WA, Australia..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Surfaces Proc & Formulat, SE-11486 Stockholm, Sweden..
    Luo, Jiangshui
    Sichuan Univ, Coll Mat Sci & Engn, Chengdu 610065, Peoples R China..
    Atkin, Rob
    Univ Western Australia, Sch Mol Sci, Perth, WA, Australia..
    Li, Hua
    Univ Western Australia, Sch Mol Sci, Perth, WA, Australia.;Univ Western Australia, Ctr Microscopy Characterisat & Anal, Perth, WA, Australia..
    Potential-Dependent Superlubricity of Ionic Liquids on a Graphite Surface2021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 7, p. 3940-3947Article in journal (Refereed)
    Abstract [en]

    The lubricities of four quaternary phosphonium ionic liquids-trihexyltetradecylphosphonium bis( 2,4,4-trimethylpentyl) phosphinate ([P-6,P-6,P-6,P-14][(C-1(8))(2)PO2]), trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate ([P-6,P-6,P-6,P-14][ BEHP]), trihexyltetradecylphosphonium bis-(trifluoromethylsulfonyl) imide ([P-6,P-6,P-6,P-14][TFSI]), and tributylmethylphosphonium bis(trifluoromenthylsulfonyl)imide ([P-4,P-4,P-4,P-1][TFSI])-were measured as a function of potential on highly oriented pyrolytic graphite (HOPG) by using atomic force microscopy (AFM). The shear strength and surface contact radius values fitted from JKR model indicate the AFM probe slides on an IL boundary layer rather than bare HOPG. Frictions change as the compositions of the boundary layers switch from cation enriched to anion enriched when the potential changes from negative to positive. Superlubricity, which refers to near zero increase in friction with load, is achieved for the [P-6,P-6,P-6,P-14](+) cation at -1.0 V and the [TFSI](-) anion at +1.0 V. The lubricities of ILs are mainly influenced by three factors: the alkyl chain length, chemical composition, and ion sizes.

  • 1375. Zhang, Zhisen
    et al.
    Shen, Jiawei
    Wang, Hongbo
    Wang, Qi
    Zhang, Junqiao
    Liang, Lijun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tu, Yaoquan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Effects of Graphene Nanopore Geometry on DNA Sequencing2014In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, no 9, p. 1602-1607Article in journal (Refereed)
    Abstract [en]

    In this Letter we assess the effect of graphene nanopore geometries on DNA sequencing by considering DNA fragments including A, T, C, G, and 5-methylcytosine (MC) pulled out of graphene nanopores of different geometries with diameters down to similar to 1 nm. Using steered molecular dynamics simulations it is demonstrated that the bases (A, T, C, G, and MC) can be indentified at single-base resolution through the characteristic peaks on the force profile in a circular graphene nanopore but not in nanopores with other asymmetric geometries. Our study suggests that the graphene nanopore surface should be modified as symmetrically as possible in order to sequence DNA by atomic force microscopy or optical tweezers.

  • 1376.
    Zhao, Ke
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Liu, Peng-Wei
    Wang, Chuan-Kui
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Effects of Structural Fluctuations on Two-Photon Absorption Activity of Interacting Dipolar Chromophores2010In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 33, p. 10814-10820Article in journal (Refereed)
    Abstract [en]

    One- and two-photon absorption properties of organic chromophores consisting of interacting dipolar branches have been studied using density functional response theory in combination with molecular dynamics simulation. Effects of dipole interaction on optical absorptions have been examined. The importance of solvent effects on optical properties of charge-transfer states is explored by means of polarizable continuum model. It is found that for the interacting dipolar molecule with flexible conformations in solutions, the structural fluctuations can result in new spectral features or significant broadening of one-photon absorption spectrum. Our study highlights again the usefulness of the combined quantum chemical and molecular dynamics approach for modeling two-photon absorption materials in solutions.

  • 1377.
    Zhao, Tongyu
    et al.
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, People’s Republic of China.
    Kloc, Christian
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, People’s Republic of China.
    Ni, Wenjun
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, People’s Republic of China.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, People’s Republic of China.
    Gurzadyan, Gagik G.
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, 116024, People’s Republic of China.
    Revealing ultrafast relaxation dynamics in six-thiophene thin film and single crystal2021In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 404, article id 112920Article in journal (Refereed)
    Abstract [en]

    The excited state dynamics of six-thiophene (6T) thin film and single crystal was studied by time-resolved fluorescence and femtosecond transient absorption techniques under different excitation conditions. The dominant process in 6T system is the generation of ion pairs, dissociated to polarons staying for up to 130−3700 ns in film and 1 ms in crystal. Singlet fission (SF) was directly observed from the upper vibrational levels of the first excited singlet state S1 in 6T thin film/single crystal within 30 fs, which competes with intramolecular vibrational relaxation. Triplet state lifetime is dramatically shortened from 6T single crystal (1 ms) to thin film (4 ns) due to triplet-triplet annihilation, which is influenced by structural defects in amorphous regions of 6T film. Compared with 6T crystal, the partially ordered semicrystalline morphology of 6T film suggests the impact of well-structured crystallinity and molecular packing on the photocarriers transport dynamics and lifetime of triplet state. Moreover, excitation to upper excited singlet state (4.96 eV) leads to a higher yield of polarons (factor of 4), while SF in film/crystal is fully suppressed. Existence of long-lived photogenerated polarons may count π-conjugated oligomers as promising materials for developing organic-molecule-based optoelectroinc devices.

  • 1378.
    Zhao, Yihao
    et al.
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang.
    Zhang, Jintu
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang; CarbonSilicon AI Technology Company, Ltd., Hangzhou 310018, Zhejiang, China, Zhejiang.
    Zhang, Haotian
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang; CarbonSilicon AI Technology Company, Ltd., Hangzhou 310018, Zhejiang, China, Zhejiang.
    Gu, Shukai
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang.
    Deng, Yafeng
    CarbonSilicon AI Technology Company, Ltd., Hangzhou 310018, Zhejiang, China, Zhejiang.
    Tu, Yaoquan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Theoretical Chemistry and Biology.
    Hou, Tingjun
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang.
    Kang, Yu
    College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China, Zhejiang.
    Sigmoid Accelerated Molecular Dynamics: An Efficient Enhanced Sampling Method for Biosystems2023In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 14, no 4, p. 1103-1112Article in journal (Refereed)
    Abstract [en]

    Gaussian accelerated molecular dynamics (GaMD) is recognized as a popular enhanced sampling method for tackling long-standing challenges in biomolecular simulations. Inspired by GaMD, Sigmoid accelerated molecular dynamics (SaMD) is proposed in this work by adding a Sigmoid boost potential to improve the balance between the highest acceleration and accurate reweighting. Compared with GaMD, SaMD extends the accessible time scale and improves the computational efficiency as tested in three tasks. In the alanine dipeptide task, SaMD can produce the free energy landscape with better accuracy and efficiency. In the chignolin folding task, the estimated Gibbs free energy difference can converge to the experimental value ∼30% faster. In the protein-ligand binding task, the bound conformations are closer to the crystal structure with a minimal ligand root-mean-square deviation of 1.7 Å. The binding of the ligand XK263 to the HIV protease is reproduced by SaMD in ∼60% less simulation time.

  • 1379.
    Zhao, Yilong
    et al.
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Ding, Yunxuan
    Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 310024, Hangzhou, China.
    Li, Wenlong
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China; Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 310024, Hangzhou, China.
    Liu, Chang
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Li, Yingzheng
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Zhao, Ziqi
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Shan, Yu
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Li, Fei
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China; Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 310024, Hangzhou, China.
    Li, Fusheng
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116024, Dalian, China.
    Efficient urea electrosynthesis from carbon dioxide and nitrate via alternating Cu–W bimetallic C–N coupling sites2023In: Nature Communications, E-ISSN 2041-1723, Vol. 14, no 1, article id 4491Article in journal (Refereed)
    Abstract [en]

    Electrocatalytic urea synthesis is an emerging alternative technology to the traditional energy-intensive industrial urea synthesis protocol. Novel strategies are urgently needed to promote the electrocatalytic C–N coupling process and inhibit the side reactions. Here, we report a CuWO4 catalyst with native bimetallic sites that achieves a high urea production rate (98.5 ± 3.2 μg h−1 mg−1cat) for the co-reduction of CO2 and NO3− with a high Faradaic efficiency (70.1 ± 2.4%) at −0.2 V versus the reversible hydrogen electrode. Mechanistic studies demonstrated that the combination of stable intermediates of *NO2 and *CO increases the probability of C–N coupling and reduces the potential barrier, resulting in high Faradaic efficiency and low overpotential. This study provides a new perspective on achieving efficient urea electrosynthesis by stabilizing the key reaction intermediates, which may guide the design of other electrochemical systems for high-value C–N bond-containing chemicals.

  • 1380.
    Zhou, Jingjian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Luminescent Silicon Nanocrystals: From Single Quantum Dot to Light-harvesting Devices2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

          Silicon (Si) serves as the basic material of the system-on-a-chip industry and photovoltaic panels nowadays. This is mostly thanks to its high abundance in the earth’s crust, thereby low cost, virtually non-toxicity, and superior stability. Nano-silicon, especially silicon quantum dots (Si QDs), is endowed by the quantum confinement effect with the ability to emit light efficiently under photoexcitation, different from the bulk counterpart. The bright photoluminescence (PL), first found in the 1990s, has paved the way for this nanomaterial to be applied for light conversions in the last decades, such as for biosensing/biolabeling, light emitting diodes and luminescent solar concentrators (LSCs). The latter is used to concentrate sunlight in the slab on the edge-attached solar cells by means of PL. This thesis, on the one hand, deepens the comprehension on the optical properties of Si QDs by single-dot spectroscopy; on the other hand, a low-cost mass synthesis of high-quality Si QDs is developed here, which favors high QD loading applications, demonstrated as large-area “quantum dot glass”. 

          First, the photo-physics mechanism behind PL was studied by single-dot spectroscopy, excluding the QD size inhomogeneity in the ensemble measurements. A new method was developed to fabricate large-area (~mm2) isolated oxide-passivated Si QDs on a silicon-on-insulator wafer. Linearly polarized PLs were observed on those single dots. System-limited PL linewidths, ~250 μeV, were measured at 10 K on QDs here, indicating a good quality of oxide shell endowed by high temperature annealing. Based on this method, it is possible to modify the ambient optical environment of QDs without tenuous alignments. With Si QDs residing on a metal membrane with an oxide spacer, the PL yields of single dots were enhanced ~10 times in average compared to those residing outside the membrane. Next, we have achieved, for the first time, direct observation on the temperature-dependent radiative lifetimes on single ligand-passivated Si QDs. Most importantly, these single-dot PL decays can be well-fitted mono-exponentially, indicating trap-free dynamics, as opposite to oxide-passivated counterparts.

          Secondly, a chemical synthesis method of ligand-passivated Si QDs by using triethoxysilane (TES) as precursors is introduced. The quantum yield of as-synthesized Si QDs is ~40% in solution and ~55% in Si QDs/polymer nanocomposites. Such QDs have near-unity internal quantum efficiency both in the liquid and solid phase. With a comparably good quality of Si QDs, the QD cost of this TES method is about an order of magnitude less expensive than that of the established HSQ method. 

          Finally, the application of Si QDs in photovoltaic devices was demonstrated. A 9 × 9 × 0.6 cm3 LSC device based on Si QDs was fabricated, delivering ~7.9% optical power conversion efficiency under one standard sun. This performance is very similar to the state of the art of direct-bandgap semiconductor QDs. To further expand the application area of this kind of transparent photovoltaic devices, a concept of transparent “quantum dot glass” (TQDG) is introduced, fulfilling requirements as both power-generating components and building construction materials. A 20 × 20 × 1 cm3 TQDG device was fabricated with the overall power conversion efficiency up to 1.57% and the average visible transmittance 84%. The light utilization efficiency (LUE) is 1.3%, which is among the top reported TPVs based on the LSC technology with a similar size. Moreover, to facilitate the characterization of large-area LSC-like light-harvesting devices a new concept of an “optical center” is introduced. A procedure of whole device PCE estimates from optical center excitation measurements with basic laboratory instruments was provided, with a negligible error to the measured one by the conventional method.

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    Ph.D. thesis-Jingjian Zhou
  • 1381.
    Zhou, Jingjian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Optical center of a luminescent solar concentrator2022In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794Article in journal (Refereed)
    Abstract [en]

    This letter introduces a novel approach estimating the power conversion efficiency (PCE) of a square luminescent solar concentrator (LSC) by point excitations on the “optical centers” as proposed here. Predicted by theoretical calculations, photoluminescence emissions from these optical centers experience almost the same average optical path with those from the whole device under uniform illumination. This is experimentally verified by a 20 × 20 cm2 silicon quantum dots-based LSC, with a negligible error between the predicted PCE and the measured one. This method provides a convenient way to estimate the photovoltaic performance of large-area LSC devices with basic laboratory instruments.

  • 1382. Ziolek, Marcin
    et al.
    Karolczak, Jerzy
    Zalas, Maciej
    Hao, Yan
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Douhal, Abderrazzak
    Aggregation and Electrolyte Composition Effects on the Efficiency of Dye-Sensitized Solar Cells. A Case of a Near-Infrared Absorbing Dye for Tandem Cells2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 1, p. 194-205Article in journal (Refereed)
    Abstract [en]

    Time-resolved laser spectroscopy studies of complete solar cells sensitized with a near-infrared absorbing dye (HY103) and filled with different electrolytes are applied to explain their macroscopic parameters (efficiency and short-circuit current). Particular attention is paid to the effect of coadsorbent, size of cations in electrolyte (lithium vs guanidine ones), and addition of tert-butylpyridine. A complete deactivation scheme in the cell is revealed, and the rates of electron injection and all other processes are explored. For the most efficient electrolyte, the electron injection rate constants are 0.21 ps(-1) from monomers and 0.07 ps(-1) from H-aggregates. Moreover, two important and novel findings are revealed: energy transfer from the excited state of monomers to H-aggregates (with rate constants from 0.04 to 0.25 ps(-1)) and the decrease of internal conversion rate in HY103 attached to the nanoparticles (0.01 ps(-1)) with respect to that of free dye in solution (0.06 ps(-1)). Thus, our study gives more clues to better understand the photobehavior of dye-sensitized solar cells.

  • 1383. Ziółek, M.
    et al.
    Martín, C.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Douhal, A.
    Effect of electrolyte composition on electron injection and dye regeneration dynamics in complete organic dye sensitized solar cells probed by time-resolved laser spectroscopy2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 50, p. 26227-26238Article in journal (Refereed)
    Abstract [en]

    Femtosecond time-gated fluorescence and nanosecond flash photolysis studies of seven complete, real titania nanoparticle solar cells sensitized with an efficient organic dye (TH305) were performed in order to investigate the role of the electrolyte composition on the charge transfer dynamics. The electron injection rate constants were found to range from 0.4 to 3.5 ps-1 in iodide-based electrolyte, and they well correlate with the shift of the conduction band edge potential of titania. The lithium cation additives resulted in 2 times faster electron injection rate constant (3.55 ps-1) with respect to that when larger sodium cations were used (1.86 ps-1). However, in the presence of a pyridine derivative component in the electrolyte solution, the electron injection rate constant decreased several times (0.38 ps-1 for Li+ and 0.54 ps-1 for Na+), while the electron injection efficiency was found to be still very high, 96-100%. The dye regeneration by the redox couple under relatively low fluence of excitation beam (0.4 mJ/cm2 giving about 4 electrons per titania nanoparticle) proceeds with an average rate constant of about 40 × 10 3 s-1 and efficiency close to 100%, independent of the electron composition. However, for a larger fluence (2 mJ/cm2) excitation, a titania-dye electron recombination process competes with the dye regeneration and lowers the solar cell efficiency. The effect of self-quenching, high vibrational levels of the dye excited state, and the neat solvent on the electron injection process are also discussed. This study clearly shows that for TH350-based DSSCs the best performance is obtained using Li+ and TBP as additives to the iodide electrolyte, giving the highest open circuit voltage and almost 100% efficiency of electron injection and dye regeneration.

  • 1384.
    Zou, Haiyuan
    et al.
    Harbin Inst Technol, Sch Chem & Chem Engn, 92 West Da Zhi St, Harbin 150001, Heilongjiang, Peoples R China.;Southern Univ Sci & Technol, Dept Chem, Shenzhen 518055, Peoples R China.;Southern Univ Sci & Technol, Shenzhen Grubbs Inst, Shenzhen 518055, Peoples R China..
    Li, Ge
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Duan, Lele
    Southern Univ Sci & Technol, Dept Chem, Shenzhen 518055, Peoples R China.;Southern Univ Sci & Technol, Shenzhen Grubbs Inst, Shenzhen 518055, Peoples R China..
    Kou, Zongkui
    Harbin Inst Technol, Sch Chem & Chem Engn, 92 West Da Zhi St, Harbin 150001, Heilongjiang, Peoples R China.;Natl Univ Singapore, Dept Mat Sci & Engn, Singapore 117574, Singapore..
    Wang, John
    Natl Univ Singapore, Dept Mat Sci & Engn, Singapore 117574, Singapore..
    In situ coupled amorphous cobalt nitride with nitrogen-doped graphene aerogel as a trifunctional electrocatalyst towards Zn-air battery deriven full water splitting2019In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 259, article id UNSP 118100Article in journal (Refereed)
    Abstract [en]

    Herein, we report a new type of efficient trifunctional electrocatalyst by in situ coupling amorphous cobalt nitride (CoNx) nanoparticles within three-dimensional (3D) nitrogen-doped graphene aerogel (NGA). The CoNx/NGA nanohybrid with hierarchical porous strucuture guarantees the superior activities toward ORR, OER and HER, due to abundant dual active CoNx. and NxC sites. Impressively, it also exhibits a long lifetime and exceptionally high electrochemical performances as a cathode and an anode in a two-electrode overall water splitting electrolyzer, and also as an air-cathode in a rechargeable Zn-air battery. In addition, the CoNx/NGA-based water splitting electrolyzer and two Zn-air batteries can be integrated together to effectively self-drive electrochemical water splitting device with high gas evolution rates of 186 and 372 mu mol h(-1) for O-2 and H-2, respectively. This work paves a way for designing advanced non-noble multifunctional catalysts, aiming for the real application of energy storage and conversion devices.

  • 1385.
    Zou, Yuqin
    et al.
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany.
    Eichhorn, Johanna
    Walter Schottky Institute and Physics Department, Technische Universität München, Am Coulombwall 4, Garching, 85748, Germany.
    Rieger, Sebastian
    Chair for Photonics and Optoelectronics, Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstr. 10, München, 80539, Germany.
    Zheng, Yiting
    School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
    Yuan, Shuai
    Department of Chemistry, Renmin University of China, No. 59 Zhongguancun Street, Beijing, 100872, China.
    Wolz, Lukas
    Walter Schottky Institute and Physics Department, Technische Universität München, Am Coulombwall 4, Garching, 85748, Germany.
    Spanier, Lukas V.
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany.
    Heger, Julian E.
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany.
    Yin, Shanshan
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany.
    Everett, Christopher R.
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany.
    Dai, Linjie
    Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom.
    Schwartzkopf, Matthias
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, Hamburg, 22607, Germany.
    Mu, Cheng
    Department of Chemistry, Renmin University of China, No. 59 Zhongguancun Street, Beijing, 100872, China.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, Hamburg, 22607, Germany.
    Sharp, Ian D.
    Walter Schottky Institute and Physics Department, Technische Universität München, Am Coulombwall 4, Garching, 85748, Germany.
    Chen, Chun-Chao
    School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
    Feldmann, Jochen
    Chair for Photonics and Optoelectronics, Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstr. 10, München, 80539, Germany.
    Stranks, Samuel D.
    Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom; Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom.
    Müller-Buschbaum, Peter
    Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, Garching, 85748, Germany; Heinz Maier-Leibnitz-Zentrum (MLZ), Technical University of Munich, Lichtenbergstr. 1, Garching, 85748, Germany.
    Ionic liquids tailoring crystal orientation and electronic properties for stable perovskite solar cells2023In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 112, p. 108449-108449, article id 108449Article in journal (Refereed)
    Abstract [en]

    The crystallization behavior of perovskite films has a profound influence on the resulting defect densities, charge carrier dynamics and photovoltaic performance. Herein, we introduce ionic liquids into the perovskite component to tailor the crystal growth of perovskite films from a disordered to a preferential corner-up orientation and accordingly increase the charge carrier mobility to accelerate electron transport and extraction. Using time-resolved measurements, we probe the charge carrier generation, transport and recombination behavior in these films and related devices. We find the ionic liquid-containing samples exhibit lower defects, faster charge carrier transport and suppressed non-radiative recombination, contributing to higher efficiency and fill factor. Via operando grazing-incidence small- and wide-angle X-ray scattering measurements, we observe a light-induced lattice compression and grain fragmentation in the control devices, whereas the ionic liquid-containing devices exhibit a slight light-induced crystal reconstitution and stronger tolerance against illumination. Under ambient conditions, the non-encapsulated device with the pyrrolidinium-based ionic compound (Pyr14BF4) maintains 97% of its initial efficiency after 4368 h.

  • 1386.
    Zou, Yuqin
    et al.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Yuan, Shuai
    Renmin Univ China, Dept Chem, Beijing 100872, Peoples R China..
    Buyruk, Ali
    Univ Munich LMU, Chair Phys Chem, Dept Chem, D-81377 Munich, Germany.;Univ Munich LMU, Ctr NanoSci CeNS, D-81377 Munich, Germany..
    Eichhorn, Johanna
    Tech Univ Munich, Walter Schottky Inst, D-85748 Garching, Germany.;Tech Univ Munich, Phys Dept, D-85748 Garching, Germany..
    Yin, Shanshan
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Reus, Manuel A.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Xiao, Tianxiao
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Pratap, Shambhavi
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Liang, Suzhe
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Weindl, Christian L.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Chen, Wei
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Mu, Cheng
    Renmin Univ China, Dept Chem, Beijing 100872, Peoples R China..
    Sharp, Ian D.
    Tech Univ Munich, Walter Schottky Inst, D-85748 Garching, Germany.;Tech Univ Munich, Phys Dept, D-85748 Garching, Germany..
    Ameri, Tayebeh
    Univ Munich LMU, Chair Phys Chem, Dept Chem, D-81377 Munich, Germany.;Univ Munich LMU, Ctr NanoSci CeNS, D-81377 Munich, Germany..
    Schwartzkopf, Matthias
    DESY, D-22607 Hamburg, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. DESY, D-22607 Hamburg, Germany..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, D-85748 Garching, Germany..
    The Influence of CsBr on Crystal Orientation and Optoelectronic Properties of MAPbI(3)-Based Solar Cells2022In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 14, no 2, p. 2958-2967Article in journal (Refereed)
    Abstract [en]

    Crystal orientations are closely related to the behavior of photogenerated charge carriers and are vital for controlling the optoelectronic properties of perovskite solar cells. Herein, we propose a facile approach to reveal the effect of lattice plane orientation distribution on the charge carrier kinetics via constructing CsBr-doped mixed cation perovskite phases. With grazing-incidence wide-angle X-ray scattering measurements, we investigate the crystallographic properties of mixed perovskite films at the microscopic scale and reveal the effect of the extrinsic CsBr doping on the stacking behavior of the lattice planes. Combined with transient photocurrent, transient photovoltage, and space-charge-limited current measurements, the transport dynamics and recombination of the photogenerated charge carriers are characterized. It is demonstrated that CsBr compositional engineering can significantly affect the perovskite crystal structure in terms of the orientation distribution of crystal planes and passivation of trap-state densities, as well as simultaneously facilitate the photogenerated charge carrier transport across the absorber and its interfaces. This strategy provides unique insight into the underlying relationship between the stacking pattern of crystal planes, photogenerated charge carrier transport, and optoelectronic properties of solar cells.

  • 1387.
    Zou, Zhi
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. zhizou@kth.se.
    Liu, Longcheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Meng, S.
    Bian, Xiaolei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Li, Y.
    Applicability of different double‐layer models for the performance assessment of the capacitive energy extraction based on double layer expansion (Cdle) technique2021In: Energies, E-ISSN 1996-1073, Vol. 14, no 18, p. 5828-, article id 5828Article in journal (Refereed)
    Abstract [en]

    Capacitive energy extraction based on double layer expansion (CDLE) is a renewable method of harvesting energy from the salinity difference between seawater and freshwater. It is based on the change in properties of the electric double layer (EDL) formed at the electrode surface when the concentration of the solution is changed. Many theoretical models have been developed to describe the structural and thermodynamic properties of the EDL at equilibrium, e.g., the Gouy– Chapman–Stern (GCS), Modified Poisson–Boltzmann–Stern (MPBS), modified Donnan (mD) and improved modified Donnan (i‐mD) models. To evaluate the applicability of these models, especially the rationality and the physical interpretation of the parameters that were used in these models, a series of single‐pass and full‐cycle experiments were performed. The experimental results were compared with the numerical simulations of different EDL models. The analysis suggested that, with optimized parameters, all the EDL models we examined can well explain the equilibrium charge–voltage relation of the single‐pass experiment. The GCS and MPBS models involve, how-ever, the use of physically unreasonable parameter values. By comparison, the i‐mD model is the most recommended one because of its accuracy in the results and the meaning of the parameters. Nonetheless, the i‐mD model alone failed to simulate the energy production of the full‐cycle CDLE experiments. Future research regarding the i‐mD model is required to understand the process of the CDLE technique better.

  • 1388.
    Zschiesche, Hannes
    et al.
    Max Planck Inst Colloids & Interfaces, Dept Colloid Chem, Potsdam, Germany..
    Soroka, Inna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Tarakina, Nadezda V.
    Max Planck Inst Colloids & Interfaces, Dept Colloid Chem, Potsdam, Germany..
    Non-classical crystallization of CeO2 by means of in situ electron microscopy2023In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, article id d3nr02400Article in journal (Refereed)
    Abstract [en]

    During in situ liquid-phase electron microscopy (LP-EM) observations, the application of different irradiation dose rates may considerably alter the chemistry of the studied solution and influence pro-cesses, in particular growth pathways. While many processes have been studied using LP-EM in the last decade, the extent of the influence of the electron beam is not always understood and comparisons with corresponding bulk experiments are lacking. Here, we employ the radiolytic oxidation of Ce3+ in aqueous solution as a model reaction for the in situ LP-EM study of the formation of CeO2 particles. We compare our findings to the results from our previous study where a larger volume of Ce3+ precursor solution was subjected to ?-irradiation. We systematically analyze the effects of the applied irradiation dose rates and the induced diffusion of Ce ions on the growth mechanisms and the morphology of ceria particles. Our results show that an eight orders of magnitude higher dose rate applied during homogeneous electron-radiation in LP-EM compared to the dose rate using gamma-radiation does not affect the CeO2 particle growth pathway despite the significant higher Ce3+ to Ce4+ oxidation rate. Moreover, in both cases highly ordered structures (mesocrystals) are formed. This finding is explained by the stepwise formation of ceria particles via an intermediate phase, a signature of non-classical crystallization. Furthermore, when irradiation is applied locally using LP scanning transmission electron microscopy (LP-STEM), the higher conversion rate induces Ce-ion concentration gradients affecting the CeO2 growth. The appearance of branched morphologies is associated with the change to diffusion limited growth.

  • 1389.
    Öberg, Helena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fragment molecular orbital study of the cAMP-dependent protein kinase catalyzed phosphoryl transfer: a comparison with the differential transition state stabilization method2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 22, p. 15153-15161Article in journal (Refereed)
    Abstract [en]

    The importance of key residues to the activity of the cAMP-dependent protein kinase catalyzed phosphoryl transfer and to the stabilization of the transition state of the reaction has been investigated by means of the fragment molecular orbital (FMO) method. To evaluate the accuracy of the method and its capability of fragmenting covalent bonds, we have compared stabilization energies due to the interactions between individual residues and the reaction center to results obtained with the differential transition state stabilization method (Szarek, et al., J. Phys. Chem. B, 2008, 112, 11819-11826) and observe, despite a size difference in the fragment describing the reaction center, near-quantitative agreement. We have also computed deletion energies to investigate the effect of virtual deletion of key residues on the activation energy. These results are consistent with the stabilization energies and yield additional information as they clearly capture the effect of secondary interactions, i. e. interactions in the second coordination layer of the reaction center. We find that using FMO to calculate deletion energies is a powerful and time efficient approach to analyze the importance of key residues to the activity of an enzyme catalyzed reaction.

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    fulltext
  • 1390.
    Öhman, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Development of ATR-FTIR Kretschmann Spectroscopy for In situ Studies of Metal / Polymer Interfaces: and its Intergration with EIS for Exposure to Corrosive Conditions2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The environmental stability of a metal / polymer interface is essential for the durability and mechanical stability of constructions in several important areas such as the automotive, offshore, building and aerospace industries. The protective capability of a polymer film is strongly connected to its barrier properties, but the transport of water and corrosive constituents through the polymer and the subsequent processes at the metal surface are complicated to analyse in detail. The surface to be analysed is confined between two media that are impermeable to most probing particles used in conventional analytical techniques. Several methods exist to describe separate parts of the system, but few techniques work atambient pressure and have the capacity to conduct real-time analysis at relevant exposure conditions. In this work, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) in the Kretschmann geometry was successfully employed for systematic studies of metal / polymer interfaces. This technique requires the use of thin metal films deposited on an internal reflection element (IRE). Most studies were performed on aluminium, which is an important structural light-weight material, but also zinc was analysed, being frequently used for corrosion protection of steel. Upon exposure to water and electrolytes, the ATR-FTIR Kretschmann technique was found capable to monitor and to separate early deterioration related processes at the aluminium / polymer interface, including water sorption and transport of ionic species through the polymer film. Other main processes identified were the formation of corrosion products and swelling of the surface-near polymer network. To perform more comprehensive interpretations, a spectro-electrochemical method was further developed for in situ studies of the hidden metal / polymer interfaces. The ATR-FTIR Kretschmann technique was here combined with the complementary acting technique, Electrical Impedance Spectroscopy (EIS). The integrated set-up was able to provide complementary information, with ATR-FTIR Kretschmann being sensitive to the surface-near region and EIS to the whole system. For instance, metal oxidation and delamination processes can be difficult to distinguish by EIS, while on the other hand oxidation and hydration reactions on aluminiumcan be confirmed as IR bands at distinct positions. Delamination and swelling of a polymer both result in negative bands in an IR spectrum, but these processes may be distinguished by EIS as alterations in different frequency regions. While traditional chemical pre-treatments for enhanced hydrolytic stability perform excellent, they are being phased out from industrial applications due to environmental concerns and work health issues. Today there is an intense ongoing research regarding the mechanisms and performance of environmentally friendly pretreatments to develop systems of similar performance, and the analysis of the confined metal / polymer interface is crucial for this development. The capability of the integrated in situ ATR-FTIR Kretschmann and EIS set-up was therefore further applied to systems where a surface pre-treatment had been applied to the metal prior to the organic coating. Studies were first performed on vacuum-evaporated films of zinc treated with a titanium-based conversion coating and further coated with a UV-curing polymer. Alterations of the conversion layer could be detected upon exposure to the electrolyte. Also alkaline-cleaned aluminium coated with an amino-functional silane film and a thermo-curing epoxy top-coat was thoroughlycharacterized by both ATR-FTIR and IRRAS and further investigated upon exposure toelectrolyte and humid air. Changes at the hidden interface were detected upon thermal curingof the epoxy film and during exposure in electrolyte, and the in situ ATR-FTIR Kretschm annanalysis showed a high sensitivity towards alterations in the interfacial region. Complementary studies in the absence of metal could confirm a water uptake within the silane film and water-induced alterations of the siloxane network.

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    FULLTEXT02
  • 1391.
    Öhman, Sebastian
    et al.
    Department of Chemistry, Inorganic Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala SE-75121, Sweden.
    Forslund, Axel
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Lindblad, Rebecka
    Department of Physics and Astronomy, X-ray Photon Science, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
    Nagy, Gyula
    Department of Physics and Astronomy, Applied Nuclear Physics, Ångström Laboratory, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
    Broqvist, Peter
    Department of Chemistry, Structural Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala SE-75121, Sweden.
    Berggren, Elin
    Department of Physics and Astronomy, X-ray Photon Science, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
    Johansson, Fredrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France.
    Törndahl, Tobias
    Department of Materials Science and Engineering, Solar Cell Technology, Ångström Laboratory, Uppsala University, Box 35, Uppsala SE-75103, Sweden.
    Primetzhofer, Daniel
    Department of Physics and Astronomy, Applied Nuclear Physics, Ångström Laboratory, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
    Boman, Mats
    Department of Chemistry, Inorganic Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala SE-75121, Sweden.
    Role of Oxygen in Vacancy-Induced Phase Formation and Crystallization of Al2TiO5-Based Chemical Vapor-Deposited Coatings2023In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 13, p. 6456-6465Article in journal (Refereed)
    Abstract [en]

    Oxygen is a commonly overlooked element influencing the properties of many metal oxides. By combining several analytical in situ techniques and theoretical calculations, we demonstrate that oxygen plays a vital part in the phase formation and crystallization of Al2TiO5-based chemical vapor-deposited coatings. Rutherford backscattering spectrometry (RBS) corroborates a polymorphic transformation during crystallization. Subsequent hard X-ray photoelectron spectroscopy (HAXPES) shows that crystallization occurs through a displacive (diffusionless) mechanism. Coupled with theoretical calculations, the crystallization and co-formation of Al2TiO5, Al6Ti2O13, and Al16Ti5O34 are suggested to be driven by the migration of oxygen ions and their corresponding vacancies.

  • 1392. Öjekull, J.
    et al.
    Andersson, P. U.
    Någård, M. B.
    Pettersson, J. B. C.
    Neau, A.
    Rosén, S.
    Thomas, R. D.
    Larsson, M.
    Semaniak, J.
    Österdahl, Fabian
    KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
    Danared, H.
    Källberg, A.
    af Ugglas, M.
    Dissociative recombination of ammonia clusters studied by storage ring experiments2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 125, no 19, p. 194306-Article in journal (Refereed)
    Abstract [en]

    Dissociative recombination of ammonia cluster ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for dissociative recombination of H+(NH3)(2), H+(NH3)(3), D+(ND3)(2), and D+(ND3)(3) in the collision energy range of 0.001-27 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 1000 K are calculated from the experimental data and compared with earlier results. The fragmentation patterns for the two ions H+(NH3)(2) and D+(ND3)(2) show no clear isotope effect. Dissociative recombination of X+(NX3)(2) (X=H or D) is dominated by the product channels 2NX(3)+X [0.95 +/- 0.02 for H+(NH3)(2) and 1.00 +/- 0.02 for D+(ND3)(2)]. Dissociative recombination of D+(ND3)(3) is dominated by the channels yielding three N-containing fragments (0.95 +/- 0.05).

  • 1393.
    Önsten, Anneli
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Stoltz, Dunja
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Palmgren, Pål
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Water Adsorption on ZnO(0001): Transition from Triangular Surface Structures to a Disordered Hydroxyl Terminated phase2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 25, p. 11157-11161Article in journal (Refereed)
    Abstract [en]

    We present room temperature scanning tunneling microscopy and photoemission spectroscopy studies of water adsorption on the Zn-terminated ZnO(0001) surface. Data indicates that the initial adsorption is dissociative leaving hydroxyl groups on the surface. At low water coverage, the adsorption occurs next to the oxygen-terminated step edges, where water is believed to bind to zinc cations leaving off hydrogen atoms to under-coordinated oxygen anions. When increasing the water dose, triangular terraces grow in size and pits diminish until the surface is covered with wide irregular terraces and a large number of small pits. Higher water exposure (20 Langmuir) results in a much more irregular surface. Hydrogen, which is produced in the dissociation reaction is believed to have an important role in the changed surface structure at high exposures. The fact that adsorbed water completely changes the structure of ZnO(0001) is an important finding toward the understanding of this surface at atmospheric conditions.

  • 1394.
    Önsten, Anneli
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Stoltz, Dunja
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Role of defects in surface chemistry on Cu2O(111)2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 38, p. 19357-19364Article in journal (Refereed)
    Abstract [en]

    High-resolution photoemission spectroscopy and scanning tunneling microscopy (STM) have been used to investigate defects on Cu2O(111) and their interaction with water and sulfur dioxide (SO2). Two types of point defects, i.e., oxygen and copper vacancies, are identified. Copper vacancies are believed to be the most important defects in both water and SO2 surface chemistry. Multiply coordinatively unsaturated oxygen anions (OMCUS) such as oxygen anions adjacent to copper vacancies are believed to be adsorption sites for both water and SO2 reaction products. Water adsorption at 150 K results in both molecular and dissociated water. Molecular water leaves the surface at 180 K. At 300 K and even more at 150 K, SO2 interacts with oxygen sites at the surface forming SO 3 species. However, thermal treatment up to 280 K of Cu 2O(111)/SO2 prepared at 150 K renders only SO4 on the surface.

  • 1395.
    Örnek, Cem
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Swerea KIMAB AB, Department of Corrosion in Energy and Process Industry.
    Liu, Min
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, National Center for Materials Service Safety.
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Jin, Ying
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study2018In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 61, no 9-11, p. 1169-1182Article in journal (Refereed)
    Abstract [en]

    In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg2Si and Al2Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP’s). The Volta potential difference between the IMP’s and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML’s of water. This can lead to nobility inversions of the IMP’s relative to the aluminum matrix. The measured Volta potential difference between both IMP’s and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP’s with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al2Cu remained with the introduction of RH, whereas Mg2Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP’s in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure.

  • 1396.
    Österdahl, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of iron fluoride trihydrate from mixed acid solutions2005Licentiate thesis, comprehensive summary (Other scientific)
  • 1397.
    Östmark, Emma
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Macakova, Lubica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Auletta, Tommaso
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Dendritic Structures Based on Bis(hydroxymethyl)propionic Acid as Platforms for Surface Reactions2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 10, p. 4512-4519Article in journal (Refereed)
    Abstract [en]

    In this paper we present results related to the self-assembly of different generations of disulfide-cored 2,2-bis(hydroxymethyl)propionic acid-based dendritic structures onto gold surfaces. These molecular architectures, ranging from generation 1 to generation 3, contain removable acetonide protecting groups at their periphery that are accessible for hydrolysis with subsequent formation of OH-terminated surface-attached dendrons. The deprotection has been investigated in detail as a versatile approach to accomplish reactive surface platforms. A special focus has been devoted to the comparison of the properties of the layers formed by hydrolysis of the acetonide moieties directly on the surface and in solution, prior to the layer formation.

  • 1398.
    Özeren, Hüsamettin Deniz
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Plasticization of Biobased Polymers: A Combined Experimental and Simulation Approach2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The field of bio-based plastics has developed significantly in recent decades and there is an increasing demand for industries to shift from petrochemical to biobased polymers. Biobased polymers offer competitive properties, and in many cases have advantages in terms of cost. Thermoplastic starch is already commercially available, while wheat-gluten protein-based materials are considered to be promising candidates for commercial use.

    Biobased materials can, however, have several drawbacks that have to be handled. Starch-based materials are, in general, brittle due to the stiff glucose-based molecular chain and hydrogen bond network. This is the case also for proteins (due to the stiff peptide bond, bulky side groups and hydrogen bond network), like for example gluten. These issues can, however, be resolved with effective compatible plasticizers. But in order to be able to optimize the choice of the right plasticizer for a specific polymer, there is a need for an increased understanding of the plasticizer mechanisms. Besides, a methodology for prediction of the plasticizer amount needed, as well as to be able to rank possible plasticizer candidates, based on their effectiveness.    

    As a part of the development of a methodology (based on the combination of experimental and molecular-dynamics simulations) for prediction of plasticization and to investigate and understand plasticizer mechanisms, the main material investigated was starch, but also wheat gluten, both plasticized with glycerol. The main plasticizer used to date for biobased polymer materials is glycerol, because of its effectiveness, stability and low cost. In addition, it is also a large byproduct of biodiesel production. A number of other plasticizer candidates were also studied for the starch system to see if the developed methodology could be used to rank plasticizers. Diols were tested in the starch system as plasticizers, but they had no or little plasticization effect. Nevertheless, they gave rise to unexpected structures and properties. Several techniques were used to determine the experimental properties of the bio-based films, including calorimetry, gravimetry, dynamic mechanical analysis, and tensile testing.

    The results (based on mechanical and thermal properties) showed that the methodology could be used to rank plasticizers in terms of their effectiveness. It was also possible to predict the amount of plasticizer needed for effective softening. With the help of the simulations, the emollient effect could be studied in detail and largely explained by hydrogen bonding effects. The methodology was also developed to be able to predict from simulation not only trends in mechanical properties but also absolute values ​​in stiffness and strength at elongation rates corresponding to experimental measurements.

  • 1399.
    Özeren, Hüsamettin Deniz
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Wei, Xin-Feng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Nilsson, Fritjof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Olsson, Richard
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Role of Hydrogen Bonding in Wheat Gluten Protein Systems Plasticized with Glycerol and Water2021In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 232, p. 124149-Article in journal (Other academic)
    Abstract [en]

    Many biopolymers are stiff and brittle and require plasticizers. To optimize the choice and amount of plasticizer, the mechanisms behind plasticization need to be understood. For polar biopolymers, such as polysaccharides and proteins, plasticization depends to a large extent on the hydrogen bond network. In this study, glycerol-plasticized protein systems based on wheat gluten were investigated, in combination with the effects of water. The methodology was based on a combination of mechanical tests and molecular dynamics simulations (MD). The simulations accurately predicted the glycerol content where the experimental depression in glass transition temperature (Tg) occurred (between 20 and 30 wt.% plasticizer). They also predicted the strong water-induced depression in Tg. Detailed analysis revealed that in the dry system, the main effect of glycerol was to break protein-protein hydrogen bonds. In the moist system, glycerol was partly outcompeted by water in forming hydrogen bonds with the protein, making the glycerol plasticizer less effective than in dry conditions. These results show that MD can successfully predict the plasticizer concentration at which the onset of efficient plasticization occurs. MD can therefore be an important tool for understanding plasticizer mechanisms, even in a complex system, on a level of detail that is impossible with experiments.

25262728 1351 - 1399 of 1399
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