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  • 101.
    Eriksson, Adam
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Kürten, Charlotte
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Syrén, Per-Olof
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Protonation-Initiated Cyclization by a ClassII Terpene Cyclase Assisted by Tunneling2017In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 18, no 23, p. 2301-2305Article in journal (Refereed)
    Abstract [en]

    Terpenes represent one of the most diversified classes of natural products with potent biological activities. The key to the myriad of polycyclic terpene skeletons with crucial functions in organisms from all kingdoms of life are terpene cyclase enzymes. These biocatalysts enable stereospecific cyclization of relatively simple, linear, prefolded polyisoprenes by highly complex, partially concerted, electrophilic cyclization cascades that remain incompletely understood. Herein, additional mechanistic light is shed on terpene biosynthesis by kinetic studies in mixed H2O/D2O buffers of a classII bacterial ent-copalyl diphosphate synthase. Mass spectrometry determination of the extent of deuterium incorporation in the bicyclic product, reminiscent of initial carbocation formation by protonation, resulted in a large kinetic isotope effect of up to seven. Kinetic analysis at different temperatures confirmed that the isotope effect was independent of temperature, which is consistent with hydrogen tunneling.

  • 102.
    Eriksson, Jan Christer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Henriksson, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thermodynamic Properties of Bridging Clusters in Thin Films of Water between Hydrophobic Surfaces Assessed from Surface Force Isotherms2013In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 15, p. 4789-4795Article in journal (Refereed)
    Abstract [en]

    In the course of a long-term effort to cope with surface force data for thin films of water between hydrophobic surfaces, we have applied the bridging-cluster model (Eriksson, J. C.; Henriksson, U. Bridging-cluster model for hydrophobic attraction. Langmuir 2007, 23, 10026-10033) to the recently published surface force isotherms for water films between hexadecylthiolated gold surfaces in the thickness range of 20-100 nm and temperature range of 10-40 degrees C (Wang, J.; Yoon, R.-H.; Eriksson, J. C. Excess thermodynamic properties of thin water films confined between hydrophobized gold surfaces. J. Colloid Interface Sci. 2011, 364, 257-263). We show that these isotherms can be faithfully reproduced on the basis of the bridging-cluster model. The thermodynamic excess properties (Delta G(c), Delta H-c, and T Delta S-c) of linear clusters that are assumed to bridge the core of the films were calculated from the experimental surface force isotherms. A crucial step taken was to infer two-dimensional ideal mixing of the clusters with the surrounding film water. We find that Delta H-c and T Delta S-c are both negative quantities, with the latter being larger than the former, which implies a positive excess Gibbs energy of a cluster, Delta G(c) = Delta H-c - T Delta S-c. Typically, for temperatures between 10 and 40 degrees C, these cluster properties are of the order of some k(B)T units, corresponding to 10(-4)-10(-3)k(B)T per water molecule entailed. Our analysis yields support of the notion that elongated aggregates can arise in thin films of water between hydrophobic surfaces driven by entropy of mixing.

  • 103.
    Fang, Yuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ions interacting with macromolecules: NMR studies in solution2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Specific ion effects, identified for more than hundred years, play an important role in a wide range of phenomena and applications. Several mechanisms such as direct ion interaction with molecules have been suggested to explain these effects, but quantitative experimental evidence remains scarce. Electrophoretic NMR (eNMR) has been emerging as a very powerful tool for studying molecular association and ionic transport in a variety of systems. Yet its potential in studying specific ion effect has been unexplored. In this thesis, eNMR was in part developed further as an analytical method and was in part used as one of the main techniques to study ions interacting with macromolecules in aqueous and non-aqueous solutions.

    The complexation of a large group of cations with poly ethylene oxide (PEO) in methanol was studied with eNMR. The binding of monovalent ions was demonstrated not to follow the Hofmeister order; multivalent cations except barium all showed negligible complexation. As a unifying feature, only cations with surface charge density below a threshold value were able to bind suggesting that ion solvation is critical. The binding mechanism was examined in greater detail for K+ and Ba2+ with oligomeric PEO of different chain lengths. Those two cations exhibited different binding mechanisms. K+ was found to bind to PEO by having at least 6 repeating units wrap around it while retaining the polymer flexibility. On the other hand, Ba2+ (and, to some extent, (BaAnion)+) needs a slightly shorter section to bind, but the molecular dynamics at the binding site slow considerably.

    The binding of anions with poly (N-isopropylacrylamide) in water was quantified at low salt concentration with eNMR and the binding affinity, though very weak, followed the Hofmeister order. This result indicates the non-electrostatic nature of this specific ion effects. The increase of binding strength with salt concentration is well described by a Langmuir isotherm.

    The specific ion binding to a protein, bovine serum albumin (BSA), was also studied at pH values where BSA has either net positive and negative charges. Our results show that anions have the same binding affinity irrespective of the surface charge while the binding strength of cations is reversed with the change in net surface charge. This indicates different binding mechanisms for cations and anions.

    The ionization of cellobiose in alkaline solutions was measured quantitatively by eNMR. The results show a two-step deprotonation process with increasing alkaline strength. Supported by results from 1H-13C HSQC NMR and MD simulation, ionization was proposed to be responsible for the improved solubility of cellulose in alkaline solution. eNMR was also used to characterize the effective charge of tetramethylammonium ions in a variety of solvents. In solvents of high polarity, the results agree well with predictions based on Onsager’s limiting law but for nonpolar solvents deviations were found that were attributed to ion pair formation. 

  • 104.
    Fang, Yuan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Different Binding Mechanisms of Cations and Anions to Proteins: Electrophoretic NMR Studies in Bovine Serum AlbuminManuscript (preprint) (Other academic)
  • 105.
    Fang, Yuan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Weak Anion Binding to Poly(N-isopropylacrylamide): A Quantitative Study by Electrophoretic NMRManuscript (preprint) (Other academic)
  • 106.
    Fang, Yuan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Giesecke, Marianne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Complexing Cations by Poly(ethylene oxide): Binding Site and Binding Mode2017In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 121, no 9, p. 2179-2188Article in journal (Refereed)
    Abstract [en]

    The binding of K+ and Ba2+ cations to short poly(ethylene oxide) (PEO) chains with ca. 4-25 monomeric units in methanol was studied by determining the effective charge of the polymer through a combination of electrophoretic NMR and diffusion NMR experiments. These cations were previously found to bind to long PEO chains in a similar strong manner. In addition, H-1 chemical shift and longitudinal spin relaxation rate changes upon binding were quantified. For both systems, binding was stronger for the short chains than that for the longer chains, which is attributed mainly to interactions between bound ions. For K+ ions, the equilibrium binding constant of a cation to a binding site was measured. For both cations, the binding site was estimated to consist of ca. six monomeric units that coordinated with the respective ions. For the systems with barium, a significant fraction of the bound ions are (BaAnion)(+) ion pairs. This leads to a strong anion effect in the effective charge of the oligomers acquired upon barium ion binding. For K+, the coordinating oligomer segment remains rather mobile and individual oligomers exchange rapidly (<<s) between their free and ion-complexing states. In contrast, segmental dynamics slows significantly for the oligomer section that coordinates with the barium species, and for individual oligomers, binding and nonbinding sections do not exchange on the time scale of seconds. Hence, oligomers also exchange slowly (>s) between their free and barium complexing states.

  • 107.
    Fang, Yuan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Giesecke, Marianne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Complexing Cations by Polyethylene Oxide. Binding Site and Binding Mode2017In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207Article in journal (Refereed)
  • 108.
    Fang, Yuan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yushmanov, Pavel V.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Assessing the potential of 2D electrophoretic mobility spectroscopy (2D MOSY) for analytical applications2017In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 55, no 6, p. 584-588Article in journal (Refereed)
    Abstract [en]

    Electrophoretic displacement of charged entity phase modulates the spectrum acquired in electrophoretic NMR experiments, and this modulation can be presented via 2D FT as 2D mobility spectroscopy (MOSY) spectra. We compare in various mixed solutions the chemical selectivity provided by 2D MOSY spectra with that provided by 2D diffusion-ordered spectroscopy (DOSY) spectra and demonstrate, under the conditions explored, a superior performance of the former method. 2D MOSY compares also favourably with closely related LC-NMR methods. The shape of 2D MOSY spectra in complex mixtures is strongly modulated by the pH of the sample, a feature that has potential for areas such as in drug discovery and metabolomics.

  • 109.
    Fernandes, Ricardo M. Ferreira
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dispersing Carbon Nanotubes: Towards Molecular Understanding2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon nanotubes (CNTs) exhibit unique and fascinating intrinsic electrical, optical, thermal or mechanical properties that lead to a plethora of potential applications in composite materials, electronics, energy storage, medicine, among others. However, the manipulation of nanotubes is not trivial and there are significant difficulties to overcome before achieving their full potential in applications. Because of their high aspect ratio and strong tube-to-tube van der Waals interactions, nanotubes form bundles and ropes that are difficult to disperse in liquids. In this thesis, the topic of dispersing carbon nanotubes in water was addressed by several experimental methods such as nuclear magnetic resonance (NMR) diffusometry and light/electron microcopy. The main goal was to obtain molecular information on how the dispersants interact with carbon nanotubes.

    In dispersions of single-walled carbon nanotubes (SWNTs) in water, only a small fraction of the polymeric dispersant (Pluronic F127) was shown to be adsorbed at the CNT surface. Regarding dynamic features, the residence time of F127 on the SWNT surface was measured to be in the order of hundred milliseconds, and the lateral diffusion coefficient of the polymer along the nanotube surface proved to be an order of magnitude slower than that in the solution. The surface coverage of SWNTs by F127 was also investigated and the competitive adsorption of F127 and the protein bovine serum albumin, BSA, was assessed. F127 was found to bind stronger to the CNT surface than BSA does.

    Low molecular weight dispersants, viz. surfactants, were also investigated. Using carefully controlled conditions for the sonication and centrifugation steps, reproducible sigmoidal dispersibility curves were obtained, that exhibited an interesting variation with molecular properties of the surfactants. Various metrics that quantify the ability of different surfactants to disperse CNTs were obtained. In particular, the concentration of surfactant required to attain maximal dispersibility depends linearly on alkyl chain length, which indicates that the CNT-surfactant association, although hydrophobic in nature, is different from a micellization process. No correlation between dispersibility and the critical micellization concentration, cmc, of the surfactants was found. For gemini surfactants of the n-s-n type with spacer length s and hydrophobic tail length n, the dispersibility of multiwalled carbon nanotubes (MWNTs) also followed sigmoidal curves that were compared to those obtained with single-tailed homologues. The increase in spacer length caused an increase in the dispersion efficiency. The observations indicate a loose type of monolayer adsorption rather than the formation of micelle-like aggregates on the nanotube surface. With the future goal of embedding nanotubes in liquid crystal (LC) phases and thereby creating nanocomposites, the effect of the spacer length on the thermotropic behavior of the gemini 12-s-12 surfactant was investigated. Different mesophases were observed and a non-monotonic effect of the spacer length was found and rationalized within a model of the surfactant packing in the solid state.

    The relative binding strength of simple surfactants to CNTs was assessed by the amount of F127 they displace from the CNT surface upon addition. Anionic surfactants were found to replace more F127, which was interpreted as a sign of stronger binding to CNT. The data collected for all surfactants showed a good correlation with their critical dispersibility concentration that suggests the existence of a surface coverage threshold for dispersing nanotubes.

    On the macroscopic scale, the formation of weakly bound CNT aggregates in homogeneous dispersions was found to be induced by vortex-shaking. These aggregates could quickly and easily be re-dispersed by mild sonication. This counterintuitive behavior was related to the type of dispersant used and of the duration of mechanical agitation and was explained as a result of loose coverage by the dispersant. 

  • 110.
    Fernandes, Ricardo Madeira F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. University of Porto, Portugal.
    Buzaglo, M.
    Regev, O.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Marques, E. F.
    Mechanical agitation induces counterintuitive aggregation of pre-dispersed carbon nanotubes2017In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 493, p. 398-404Article in journal (Refereed)
    Abstract [en]

    Mechanical agitation is commonly used to fragment and disperse insoluble materials in liquids. However, here we show that when pristine single-walled carbon nanotubes pre-dispersed in water are subject to vortex-shaking for very short periods (typically 10–60 s, power density ∼0.002 W mL−1), re-aggregation counterintuitively occurs. The initial dispersions are produced using surfactants as dispersants and powerful tip sonication (∼1 W mL−1) followed by centrifugation. Detailed imaging by light and electron microscopies shows that the vortex-induced aggregates consist of loose networks (1–102 μm in size) of intertwined tubes and thin bundles. The average aggregate size increases with vortexing time in an apparently logarithmic manner and depends on the dispersant used, initial concentration of nanotubes and size distribution of bundles. The aggregation is, nonetheless, reversible: if the vortex-shaken dispersions are mildly bath-sonicated (∼0.03 W mL−1), the flocs break down and re-dispersal occurs. Molecular insight for the mechanism behind this surprising phenomenon is put forth.

  • 111.
    Fernandes, Ricardo M.F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, s/n, Porto, Portugal.
    Abreu, Bárbara
    Claro, Bárbara
    Buzaglo, Matat
    Regev, Oren
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Marques, Eduardo
    Dispersing Carbon Nanotubes with Ionic Surfactants under Controlled Conditions: Comparisons and Insight2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 40, p. 10955-10965Article in journal (Refereed)
    Abstract [en]

    A fundamental understanding of the mechanisms involved in the surfactant-assisted exfoliation and dispersion of carbon nanotubes (CNTs) in water calls for well-controlled experimental methodologies and reliable comparative metrics. We have assessed the ability of several ionic surfactants to disperse single and multiwalled carbon nanotubes, resorting to a stringently controlled sonication-centrifugation method for the preparation of the dispersions. The CNT concentration was accurately measured for a wide range of surfactant concentration, using combined thermogravimetric analysis and UV–vis spectroscopy. The obtained dispersibility curves yield several quantitative parameters, which in turn allow for the effects of nanotube morphology and surfactant properties (aromatic rings, chain length, headgroup charge, andcmc) to be assessed and rationalized, both in terms of dispersed nanotube mass and surface area. The data also indicate that the CNT-surfactant association follows patterns that are markedly different from other equilibrium processes governed by hydrophobicity (such as micellization); in particular, the surfactant concentration needed for maximum dispersibility,cs,max, and the number of surfactant molecules per unit CNT area at cs,max are shown to depend linearly on chain length. The results further suggest that the presence of micelles in the exfoliation process is not a key factor either for starting CNT dispersibility or attaining its saturation value.

  • 112.
    Fernandes, Ricardo M.F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, s/n, Porto, Portugal.
    Buzaglo, Matat
    Regev, Oren
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Marques, Eduardo
    Mechanical Agitation Induces Aggregation of Pre-Dispersed Carbon Nanotubes2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Mechanical agitation is typically used to fragment and disperse insoluble materials in a solvent. We report here an aggregation process that, contrary to expectation, is induced by mechanical agitation: when aqueous dispersions of single-walled carbon nanotubes (SWNTs) are subject to vortex-shaking, weakly bound micron-sized aggregates are formed. The SWNT dispersions are prepared by adding various dispersants employing a sonication followed by centrifugation approach. While surfactant adsorption to the SWNTs during sonication results in stabilized exfoliated tubes and thin bundles, we find that vortex-shaking the fresh dispersions for short periods (10-60 s) results in re-aggregation into flocs in the 1-102 µm range. The aggregation is reversible: if the vortexed dispersions are mildly sonicated, the flocs break down and re-dispersal occurs. Imaging at different resolutions shows that the aggregates consist of loose networks of intertwined tubes and bundles. The data further indicate that the average aggregate size increases logarithmically with vortex time and is critically influenced by dispersant type (ionic or nonionic), centrifugation time (prior to vortexing) and initial concentration of dispersed SWNTs. These results are relevant if stabilization or destabilization of dispersions is sought for, i.e., in drug delivery or sensing applications, and could also be of interest for chiral sorting of SWNTs and percolation conductivity.

  • 113.
    Fernandes, Ricardo M.F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, s/n, Porto, Portugal.
    Buzaglo, Matat
    Regev, Oren
    Marques, Eduardo
    Furo, Istvan
    Surface Coverage and Competitive Adsorption on Carbon Nanotubes2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, The Journal of Physical Chemistry C, ISSN 1932-7447, Vol. 119, no 38, p. 22190-22197Article in journal (Refereed)
    Abstract [en]

    The binding strength of dispersants to the surface of carbon nanotubes is of crucial importance for the efficiency of the dispersion process and for potential applications, yet data are scarce on this subject. Here we present the results of diffusion NMR experiments in dispersions of single-walled carbon nanotubes (SWNTs) prepared by either the polymer Pluronics F127 or the protein bovine serum albumin (BSA). The experiments detect the amount of F127 molecules adsorbed onto the SWNT surface. This quantity is recorded (i) in F127-SWNT dispersions to which BSA molecules are added and (ii) in BSA-SWNT dispersions to which F127 molecules are added. The data clearly show that F127 replaces BSA adsorbed at the SWNT surface, while BSA leaves the adsorbed F127 coverage intact. Consequently, F127 binds to the nanotube surface more strongly than BSA. Hence, we provide a way to categorize dispersants by adsorption strength. We also provide evidence showing that the nanotubes dispersed by BSA form loose aggregates where a large part of the surface is not in direct contact with the surrounding liquid. The results are discussed in relation to previous findings in the literature.

  • 114.
    Fernandes, Ricardo M.F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, s/n, Porto, Portugal.
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Regev, Oren
    Marques, Eduardo
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Assessing Surfactant Binding to Carbon Nanotubes via Competitive Adsorption: Binding strength and critical coverage2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The displacement of a nonionic polymeric dispersant, Pluronic F127, adsorbed at the surface of single-walled carbon nanotubes, by low molecular-weight ionic dispersants (surfactants) is studied in aqueous dispersion. The method applied is diffusion NMR spectroscopy that can accurately measure the fraction of F127 molecules adsorbed at the tube surface because of the slow exchange (over the experimental time scale) of F127 between bulk and surface. In a series of surfactants with varying chain length and headgroups, we find that anionic surfactants replace in general more nonionic F127 than do cationic surfactants. The data collected show a strong correlation with the critical dispersibility concentration of the different surfactants, a parameter that signifies the concentration at which one obtains significant dispersed nanotube concentration by ultrasonication. We posit that this finding indicates the existence of a threshold surface coverage for dispersants that constitutes a necessary condition for de-bundling by ultrasonication. The results are discussed in relation to previous findings in the literature. 

  • 115.
    Fernandes, Ricardo M.F.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, s/n, Porto, Portugal.
    Wang, Yujie
    Tavares, Pedro
    Nunes, Sandra
    Pais, Alberto
    Marques, Eduardo
    Strong Spacer Length Effects on The Thermal Behavior and Mesophase Formation By Gemini Surfactants2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The self-aggregation properties in aqueous solution of gemini surfactants of the type alkanediyl-α,ω-bis(dodecyldimethylammonium bromides), 12-s-12, have been extensively reported and are known to be significantly influenced by the number of methylene groups, s, of the covalent spacer. In contrast, the thermal behavior of the anhydrous compounds as a function of varying s has not been investigated in a similarly systematic way. Herein, we present the thermal phase behavior of eight compounds of the 12-s-12 family (with s = 2-6, 8, 10 and 12), resorting to differential scanning calorimetry (DSC), polarized light microscopy (PLM) and X-ray diffraction (XRD). We find that compounds with either the shortest spacer, s = 2, or the longest ones—8, 10 and 12—form several smectic liquid-crystalline phases prior to isotropization to the liquid phase, with appearance of oily streaks, focal conics, mosaic and fan-shaped birefringent textures. In sharp contrast, gemini compounds with intermediate spacers, s = 3-6, decompose and do not form any disordered, fluid mesophases. Both the DSC thermodynamic parameters for the phase transitions and d00l spacings obtained from XRD show non-monotonic trends with spacer variation, indicating that there are significant differences in solid-state packing and melting process. Plausible molecular packing arrangements in the solid-state are presented, consistent with the XRD information and geometric considerations, and their influence on the phase behavior trends critically discussed.

  • 116.
    Ferreira Fernandes, Ricardo Manuel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Univ Porto, Portugal.
    Buzaglo, Matat
    Shtein, Michael
    Bar, Ilan Pri
    Regev, Oren
    Marques, Eduardo F.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Lateral Diffusion of Dispersing Molecules On Nanotubes As Probed by NMR2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 1, p. 582-589Article in journal (Refereed)
    Abstract [en]

    Noncovalent dispersion of carbon nanotubes is essential to most applications but still poorly understood at the molecular level. The interaction of the dispersing molecule with the nanotube, wrapping or nonwrapping, still awaits consensus. Herein, we have studied by H-1 NMR diffusometry some features of molecular dynamics in the system of carbon nanotubes dispersed by triblock copolymer Pluronics F127 in water. The diffusional decays obtained at different diffusion times, Delta, are not single-exponential and have a complex Delta-dependent profile, ultimately implying that the polymer is observed in two states: free (in unimeric form) and nanotube-bound. Fitting a two-site exchange model to the data indicates that at any instant, only a small fraction of polymers are adsorbed on the nanotubes, with polydisperse residence times in the range of 100-400 ms. Most significantly, we further provide an estimate of D = (3-8) x 10(-12) m(2) s(-1) the coefficient of lateral diffusion of the polymer along the nanotube surface, which is an order of magnitude slower than the corresponding self-diffusion coefficient in water. The emerging picture is that of a nonwrapping mode for the polymer-nanotube interaction.

  • 117.
    Ferreira Fernandes, Ricardo Manuel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Regev, Oren
    Marques, Eduardo
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Block copolymers adsorbed on single-walled carbon nanotubes. Block polydispersity and the modes of surface attachmentManuscript (preprint) (Other academic)
    Abstract [en]

    1H NMR peak intensities, 1H NMR diffusion measurements and TGA experiments were used to clarify the fate of the dispersing molecules, block copolymer Pluronic F127, during preparation of single-walled carbon nanotube (CNT) dispersions and their state in the created dispersions. In the dispersions, a fraction of the F127 molecules is adsorbed to the CNT surface. The mode of adsorption is the attachment and significant immobilization of the hydrophobic polypropylene oxide (PPO) block to the CNT surface and, as a result, the 1H NMR signal from the attached PPO blocks is lost. On the other hand, the hydrophilic polyethylene oxide (PEO) blocks remain highly mobile and thereby detectable by NMR. The F127 is revealed to exhibit significant block polydispersity. Molecules with large PPO blocks become enriched upon the surface of that fraction of the initial CNT powder that does not become dispersed. The molecular motions involved in creating the observed NMR features are clarified.

  • 118.
    Fidalgo, Alexandre Barreiro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dahlgren, Björn
    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.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Surface Reactions of H2O2, H-2, and O-2 in Aqueous Systems Containing ZrO22016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 3, p. 1609-1614Article in journal (Refereed)
    Abstract [en]

    In radiolysis of water, three molecular products are formed (H2O2, O-2, and H-2). It has previously been shown that aqueous hydrogen peroxide is catalytically decomposed on many oxide surfaces and that the decomposition proceeds via the formation of surface-bound hydroxyl radicals. In this work, we have investigated the behavior of aqueous H-2 and O-2 in contact with ZrO2. Experiments were carried out in an autoclave with high H2 pressure and low O-2 pressure (40 and 0.2 bar, respectively). In the experiments the concentration of H-abstracting radicals was monitored as a function of time using tris(hydroxymethyl)aminomethane (Tris) as scavenger and the subsequent formation of formaldehyde to probe radical formation. The plausible formation of H2O2 was also monitored in the experiments. In addition, density functional theory (employing the hybrid PBE0 functional) was used to search for reaction pathways. The results from the,experiments show that hydrogen-abstracting radicals: are formed in the aqueous H2O2-system in contact with solid ZrO2. Formation of H2O2 is also detected, and the time dependent production of hydrogen-abstracting radicals follows the time-dependent H2O2 concentration, strongly:indicating that the radicals are produced upon catalytic decomposition of H2O2. The DFT study implies that H2O2 formation proceeds via a pathway where HO2 is a key intermediate. It is interesting to note that all the stable molecular products from aqueous radiolysis are precursors of quite intriguing radical reactions at water/oxide interfaces.

  • 119.
    Fidalgo, Alexandre Barreiro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Can H-2 enhance the oxidative dissolution of UO2?2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 477, p. 85-87Article in journal (Refereed)
  • 120. Filippov, Andrei
    et al.
    Gnezdilov, Oleg I.
    Hjalmarsson, Nicklas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Antzutkin, Oleg N.
    Glavatskih, Sergei
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Acceleration of diffusion in ethylammonium nitrate ionic liquid confined between parallel glass plates2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 38, p. 25853-25858Article in journal (Refereed)
  • 121. Filippov, Andrey
    et al.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Khakimov, Aidar
    Grahn, Mattias
    Zhou, Han
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Antzutkin, Oleg N.
    Hedlund, Jonas
    Dynamic properties of water in silicalite-1 powder2012In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 30, no 7, p. 1022-1031Article in journal (Refereed)
    Abstract [en]

    Self-diffusion of D2O in partially filled silicalite-1 crystals was studied at 25 degrees C by H-2 nuclear magnetic resonance (NMR) with bipolar field gradient pulses and longitudinal Eddy-current-delay. For the first time, reliable experimental diffusion data for this system were obtained. Analysis of NMR diffusion decays revealed the presence of a continuous distribution of apparent self-diffusion coefficients (SDCs) of water, ranging from 10(-7) to similar to 10(-10) m(2)/s, which include values much higher and lower than that of bulk water (similar to 10(-9) m(2)/s) in liquid phase. The observed distribution of SDC changes with variation of the diffusion time in the range of 10-200 ms. A two-site Karger exchange model was successfully fitted to the data. Finally, the water distribution and exchange in silicalite-1 pores were described by taking into account (a) a gas-like phase in the zeolite pores, a gas-like phase in mesopores and an intercrystalline gas-like phase and (b) intercrystalline liquid droplets with intermediate exchange rate with the other phases. The other phases experience fast exchange on the NMR diffusion time scale. Diffusion coefficients and mean residence times of water in some of these states were estimated.

  • 122. Fink, Michael J.
    et al.
    Syrén, Per-Olof
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Redesign of water networks for efficient biocatalysis2017In: Current opinion in chemical biology, ISSN 1367-5931, E-ISSN 1879-0402, Vol. 37, p. 107-114Article, review/survey (Refereed)
    Abstract [en]

    Herein we highlight recent findings on the importance of water networks in proteins, and their redesign and reconfiguration as a new engineering strategy to generate enzymes with modulated binding affinity and improved catalytic versatility. Traditionally, enzyme engineering and drug design have focused on tailoring direct and favorable interactions between protein surfaces and ligands/transition states to achieve stronger binding, or an accelerated manufacturing of medicines, biofuels, fine chemicals and materials. In contrast, the opportunity to relocate water molecules in solvated binding pockets by protein design to improve overall energetics remains essentially unexplored, and fundamental understanding of the elusive processes involved is poor. Rewiring water networks in protein interiors impacts binding affinity, catalysis and the thermodynamic signature of biochemical processes through dynamic mechanisms, and thus has great potential to enhance binding specificity, accelerate catalysis and provide new reaction mechanisms and chemistry, that were not yet explored in nature.

  • 123.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Chlordiazepoxide dichloromethane monosolvate2012In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368Article in journal (Refereed)
    Abstract [en]

    In the title compound (systematic name: 7-chloro-2-methyl­amino-5-phenyl-3H-1,4-benzodiazepine 4-oxide dichloro­meth­ane monosolvate), C16H14ClN3O·CH2Cl2, the seven-membered ring adopts a boat conformation with the CH2 group as the prow and the two aromatic C atoms as the stern. The dihedral angle between the benzene rings is 75.25 (6)°. The crystal structure features centrosymmetric pairs of chlordiazepoxide mol­ecules linked by pairs of N—H...O hydrogen bonds, which generate R22(12) loops.

  • 124.
    Fischer, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sokka, Ilia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Belova, Liubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthesis, structure, and magnetic properties of some layered compounds based on long-chain sulfonium cations and complex cobalt and copper anions2013In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 639, no 14, p. 2613-2617Article in journal (Refereed)
    Abstract [en]

    Two new materials of the composition ({CH3(CH2) 15(CH3)2S}+)2[CoBr 4]2- (1) and ({CH3(CH2) 15(CH3)2S}+)2[CuBr 4]2- (2 and 3), of which the latter exists in two polymorphs, were synthesized. The materials display the synthetically targeted structures, comprising of layers of complex metal ions and layers of long-chain sulfonium cations. The crystal structures of the materials were determined. The interlayer distances are around 24 Å, with metal-metal distances about 8 Å. The magnetic properties of 1 were investigated, and the material is paramagnetic. ({CH3(CH2)15(CH3) 2S}+)2[CuBr4]2 is polymorphic. Both polymorphs crystallize with triclinic symmetry.

  • 125.
    Freys, Jonathan C.
    et al.
    Uppsala University.
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    D'Amario, Luca
    Uppsala University.
    Brown, Allison M.
    Uppsala University.
    Hammarström, Leif
    Uppsala University.
    Ru-based donor-acceptor photosensitizer that retards charge recombination in a p-type dye-sensitized solar cell2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 42, p. 13105-13111Article in journal (Refereed)
    Abstract [en]

    We report on the synthesis and characterization of a donor-acceptor ruthenium polypyridyl complex as a photosensitizer for p-type dye-sensitized solar cells (DSSCs). The electrochemical, photophysical, and photovoltaic performance of two ruthenium-based photosensitizers were tested in NiO-based DSSCs; bis-(2,2'-bipyridine-4,4'-dicarboxylic acid)(2)N-(1,10-phenanthroline)-4-nitronaphthalene-1,8-dicarboximide ruthenium(ii), ([Ru(dcb)(2)(NMI-phen)](PF(6))(2)) and tris-(2,2'-bipyridine-4,4'-dicarboxylic acid)(3) ruthenium(ii), [(Ru(dcb)(3))Cl(2)]. The presence of an electron-accepting group, 4-nitronaphthalene-1,8-dicarboximide (NMI), attached to the phenanthroline of [Ru(dcb)(2)(NMI-phen)](2+) resulted in long-lived charge separation between reduced [Ru(dcb)(2)(NMI-phen)](2+) and NiO valence band holes; 10-50 μs. In the reduced state for [Ru(dcb)(2)(NMI-phen)](2+), the electron localized on the distal NMI group. In tests with I(3)(-)/I(-) and Co(4,4'-di-tert-butyl-bipyridine)(3)(2+/3+) electrolytes, [Ru(dcb)(2)(NMI-phen)](2+) outperformed [Ru(dcb)(3)](2+) in solar cell efficiency in devices. A record APCE (25%) was achieved for a ruthenium photosensitizer in a p-type DSSC. Insights on photosensitizer regeneration kinetics are included.

  • 126.
    Frise, Anton
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Pages, Guilhem
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Shtein, M.
    Pri Bar, I.
    Regev, O.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Polymer binding to carbon nanotubes in aqueous dispersions: Residence time on the nanotube surface As Obtained by NMR diffusometry2012In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, no 9, p. 2635-2642Article in journal (Refereed)
    Abstract [en]

    The binding of block copolymer Pluronic F-127 in aqueous dispersions of single- (SWCNT) and multiwalled (MWCNT) carbon nanotubes has been studied by pulsed-field-gradient (PFG) 1H NMR spectroscopy. We show that a major fraction of polymers exist as a free species while a minor fraction is bound to the carbon nanotubes (CNT). The polymers exchange between these two states with residence times on the nanotube surface of 24 ± 5 ms for SWCNT and of 54 ± 11 ms for MWCNT. The CNT concentration in the solution was determined by improved thermal gravimetric analysis (TGA) indicating that the concentration of SWCNT dispersed by F-127 was significantly higher than that for MWCNT. For SWCNT, the area per adsorbed Pluronic F-127 molecule is estimated to be about 40 nm 2.

  • 127.
    Furó, Istvan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    NMR: Spectroscopy and imaging2013In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 18, no 3, p. 165-165Article in journal (Refereed)
  • 128.
    Gabrielsson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Eriksson, Susanna K.
    Gao, Jiajia
    Chen, Hong
    Li, Fusheng
    Oscarsson, Johan
    Sun, Juliang
    Resmo, Håkan
    Kloo, lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Dipicolinic Acid: A Strong Anchoring Group with Tunable Redoxand Spectral Behavior for Stable Dye-Sensitized Solar CellsManuscript (preprint) (Other academic)
  • 129.
    Gabrielsson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Uppsala University, Sweden.
    Eriksson, Susanna K.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Chen, Hong
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Oscarsson, Johan
    Sun, Junliang
    Rensmo, Håkan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian University of Technology (DUT), China.
    Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 18, p. 3858-3861Article in journal (Refereed)
    Abstract [en]

    Dipicolinic acidwas investigated as a new anchoring group for DSSCs. A pilot dye (PD2) bearing this new anchoring group was found to adsorb significantly stronger to TiO2 than its cyanoacrylic acid analogue. The electrolyte composition was found to have a strong effect on the photoelectrochemical properties of the adsorbed dye in the device, allowing the dye LUMO energy to be tuned by 0.5 eV. Using a pyridine-free electrolyte, panchromatic absorption of the dye on TiO2 extending to 900 nm has been achieved. Solar cells using PD2 and a Co(bpy)(3) based electrolyte showed unique stability under simulated sunlight and elevated temperatures.

  • 130.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Crystallography as forensic tool for electrolyte degradation in dye-sensitized solar cellsManuscript (preprint) (Other academic)
  • 131.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Electrolyte-Based Dynamics: Fundamental Studies for Stable Liquid Dye-Sensitized Solar Cells2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The long-term outdoor durability of dye-sensitized solar cells (DSSCs) is still a challenging issue for the large-scale commercial application of this promising photovoltaic technique. In order to study the degradation mechanism of DSSCs, ageing tests under selected accelerating conditions were carried out. The electrolyte is a crucial component of the device. The interactions between the electrolyte and other device components were unraveled during the ageing test, and this is the focus of this thesis. The dynamics and the underlying effects of these interactions on the DSSC performance were studied.

    Co(bpy)32+/3+-mediated solar cells sensitized by triphenylamine-based organic dyes are systems of main interest. The changes with respect to the configuration of both labile Co(bpy)32+ and apparently inert Co(bpy)33+ redox complexes under different ageing conditions have been characterized, emphasizing the ligand exchange problem due to the addition of Lewis-base-type electrolyte additives and the unavoidable presence of oxygen. Both beneficial and adverse effects on the DSSC performance have been separately discussed in the short-term and long-term ageing tests. The stability of dye molecules adsorbed on the TiO2 surface and dissolved in the electrolyte has been studied by monitoring the spectral change of the dye, revealing the crucial effect of cation-based additives and the cation-dependent stability of the device photovoltage. The dye/TiO2 interfacial electron transfer kinetics were compared for the bithiophene-linked dyes before and after ageing in the presence of Lewis base additives; the observed change being related to the light-promoted and Lewis-base-assisted performance enhancement. The effect of electrolyte co-additives on passivating the counter electrode was also observed. The final chapter shows the effect of electrolyte composition on the electrolyte diffusion limitation from the perspectives of cation additive options, cation concentration and solvent additives respectively. Based on a comprehensive analysis, suggestions have been made regarding lithium-ion-free and polymer-in-salt strategies, and also regarding cobalt complex degradation and the crucial role of Lewis base additives. The fundamental studies contribute to the understanding of DSSC chemistry and provide a guideline towards achieving efficient and stable DSSCs.

  • 132.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Impedance spectroscopic analysis of electrolyte diffusion in aged dye-sensitized solar cells containing cobalt tris(bipyridine) redox shuttlesManuscript (preprint) (Other academic)
  • 133.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Interfacial dye/electrolyte interaction dramatically improving the photocurrent in dye-sensitized solar cellsManuscript (preprint) (Other academic)
  • 134.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Light-induced cobalt tris(bipyridine) ligand exchange: a simple strategy towards efficient and durable dye-sensitized solar cellsManuscript (preprint) (Other academic)
  • 135.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bhagavathiachari, Muthuraaman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Long-term stability for cobalt-based dye-sensitized solar cells obtained by electrolyte optimization2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 47, p. 6249-6251Article in journal (Refereed)
    Abstract [en]

    A significant improvement in the long-term stability for cobalt-based dye-sensitized solar cells (DSCs) under light-soaking conditions has been achieved by optimization of the composition of tris(2,2'-bipyridine) Co(II)/Co(III) electrolytes. The effects of component exchanges and changes were also studied during the optimization process.

  • 136.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Crystallography as Forensic Tool for Understanding Electrolyte Degradation in Dye-sensitized Solar Cells2017In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 2, no 4, p. 1675-1680Article in journal (Refereed)
    Abstract [en]

    The precipitation of solid compounds from model electrolytes for liquid dye-sensitized solar cells has a story to tell regarding decomposition processes to be expected in such systems. Of course, the crystal lattice energy for a specific crystalline compounds plays a role in what compound that will eventually precipitate, but the compounds nevertheless serve as indicators for what type of processes that take place in the solar cell electrolytes upon ageing. From the compounds isolated in this study we learn that both ligand exchange processes, double-salt precipitation and oxidation are degradation processes that should not be overlooked when formulating efficient and stable electrolytes for this type of electrochemical system.

  • 137.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yang, W.
    Pazoki, M.
    Boschloo, G.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Cation-Dependent Photostability of Co(II/III)-Mediated Dye-Sensitized Solar Cells2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 44, p. 24704-24713Article in journal (Refereed)
    Abstract [en]

    The electrolyte composition has a significant effect on the performance and stability of cobalt-based, dye-sensitized solar cells (DSSCs). The stability of DSSCs incorporating Co(II/III) tris(bipyridine) redox mediator has been investigated over 1000 h under full solar irradiation (with UV cutoff) at a temperature of 60 °C, the main focus being on monitoring the photovoltaic performance of the device and analyzing the internal charge-transfer dynamics in the presence of different cation coadditives (preferably added as tetracyanoborate salts). A clear cation-dependence is shown, not only of the early light-induced performance but also of the long-term photostability of the photovoltage of the device. These light-induced changes, which are attributed to the promotion of electron injection and less electron recombination loss, by transient spectral and electrochemical studies at the TiO2/dye/electrolyte interface, indicate that the main cation effects involve the TiO2 surface electric field and energy-state distribution. By examining the stability of adsorbed and solvated dye during aging, it has been found that the dye photodegradation is probably responsible for the decline in the photovoltage and that this is extremely dependent on the nature of the cation coadditives in the electrolyte. It is therefore suggested that optimization of the electrolyte cation composition is essential for improving the stability of cobalt-based DSSCs.

  • 138.
    Gardner, James M
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Beyler, Maryline
    Uppsala University.
    Karnahl, Michael
    Uppsala University.
    Tschierlei, Stefanie
    Uppsala University.
    Ott, Sascha
    Uppsala University.
    Hammarström, Leif
    Uppsala University.
    Light-Driven Electron Transfer between a Photosensitizer and a Proton-Reducing Catalyst Co-adsorbed to NiO2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 47, p. 19322-19325Article in journal (Refereed)
    Abstract [en]

    While intermolecular hole-hopping along the surface of semiconductors is known, there are no previous examples of electron-hopping between molecules on a surface. Herein, we present the first evidence of electron transfer from the photoreduced sensitizer Coumarin-343 (C343) to complex 1, both bound on the surface of NiO. In solution, 1 has been shown to be a mononuclear Fe-based proton-reducing catalyst. The reduction of 1 is reversible and occurs within 50 ns after excitation of C343. Interfacial recombination between the reduced 1(-) and NiO hole occurs on a 100 µs time scale by non-exponential kinetics. The observed process is the first essential step in the photosensitized generation of H2 from a molecular catalyst in the absence of a sacrificial donor reagent.

  • 139. Gerts, Egor D.
    et al.
    Komolkin, Andrei V.
    Burmistrov, Vladimir A.
    Alexandriysky, Victor V.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Saint Petersburg State University, Saint Petersburg, Russia.
    Comparative study of local structure of two cyanobiphenyl liquid crystals by molecular dynamics method2014In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 141, no 7, p. 074503-Article in journal (Refereed)
    Abstract [en]

    Fully-atomistic molecular dynamics simulations were carried out on two similar cyanobiphenyl nematogens, HO-6OCB and 7OCB, in order to study effects of hydrogen bonds on local structure of liquid crystals. Comparable length of these two molecules provides more evident results on the effects of hydrogen bonding. The analysis of radial and cylindrical distribution functions clearly shows the differences in local structure of two mesogens. The simulations showed that anti-parallel alignment is preferable for the HO-6OCB. Hydrogen bonds between OH-groups are observed for 51% of HO-6OCB molecules, while hydrogen bonding between CN- and OH-groups occurs only for 16% of molecules. The lifetimes of H-bonds differ due to different mobility of molecular fragments (50 ps for N center dot center dot center dot H-O and 41 ps for O center dot center dot center dot H-O). Although the standard Optimized Potentials for Liquid Simulations - All-Atom force field cannot reproduce some experimental parameters quantitatively (order parameters are overestimated, diffusion coefficients are not reproduced well), the comparison of relative simulated results for the pair of mesogens is nevertheless consistent with the same relative experimental parameters. Thus, the comparative study of simulated and experimental results for the pair of similar liquid crystals still can be assumed plausible.

  • 140.
    Giesecke, Marianne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Characterizing ions in solution by NMR methods2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    NMR experiments performed under the effect of electric fields, either continuous or pulsed, can provide quantitative parameters related to ion association and ion transport in solution.  Electrophoretic NMR (eNMR) is based on a diffusion pulse-sequence with electric fields applied in the form of pulses. Magnetic field gradients enable the measurement of the electrophoretic mobility of charged species, a parameter that can be related to ionic association.

    The effective charge of the tetramethylammonium cation ion in water, dimethylsulphoxide (DMSO), acetonitrile, methanol and ethanol was estimated by eNMR and diffusion measurements and compared to the value predicted by the Debye-Hückel-Onsager limiting law. The difference between the predicted and measured effective charge was attributed to ion pairing which was found to be especially significant in ethanol.

    The association of a large set of cations to polyethylene oxide (PEO) in methanol, through the ion-dipole interaction, was quantified by eNMR. The trends found were in good agreement with the scarce data from other methods. Significant association was found for cations that have a surface charge density below a critical value. For short PEO chains, the charge per monomer was found to be significantly higher than for longer PEO chains when binding to the same cations. This was attributed to the high entropy cost required to rearrange a long chain in order to optimize the ion-dipole interactions with the cations. Moreover, it was suggested that short PEO chains may exhibit distinct binding modes in the presence of different cations, as supported by diffusion measurements, relaxation measurements and chemical shift data.

    The protonation state of a uranium (VI)-adenosine monophosphate (AMP) complex in aqueous solution was measured by eNMR in the alkaline pH range. The question whether or not specific oxygens in the ligand were protonated was resolved by considering the possible association of other species present in the solution to the complex.

    The methodology of eNMR was developed through the introduction of a new pulse-sequence which suppresses artifactual flow effects in highly conductive samples.

    In another experimental setup, using NMR imaging, a constant current was applied to a lithium ion (Li ion) battery model. Here, 7Li spin-echo imaging was used to probe the spin density in the electrolyte and thus visualize the development of Li+ concentration gradients. The Li+ transport number and salt diffusivity were obtained within an electrochemical transport model. The parameters obtained were in good agreement with data for similar electrolytes. The use of an alternative imaging method based on CTI (Constant Time Imaging) was explored and implemented.

  • 141.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Constant-time chemical-shift selective imaging2013In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 226, p. 19-21Article in journal (Refereed)
    Abstract [en]

    We demonstrate that chemical-shift-selective constant-time imaging (CTI) can be performed by simply inserting selective saturation into the original imaging pulse sequence. The performance of the proposed method is illustrated by 7Li CTI imaging in a battery model that contains both Li metal electrodes and an electrolyte containing a dissolved Li salt.

  • 142.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fang, Yuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Binding modes of cations to polyethylene oxide: An NMR studyManuscript (preprint) (Other academic)
  • 143.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hallberg, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fang, Yuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stilbs, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Binding of monovalent and multivalent metal cations to polyethylene oxide in methanol probed by electrophoretic and diffusion NMR2016In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 120, no 39, p. 10358-10366Article in journal (Refereed)
    Abstract [en]

    Complex formation in methanol between monodisperse polyethylene oxide (PEO) and a large set of cations was studied by measuring the effective charge acquired by PEO upon complexation. Quantitative data were obtained at a low ionic strength of 2 mM (for some salts, also between 0.5 and 6 mM) by a combination of diffusion nuclear magnetic resonance (NMR) and electrophoretic NMR experiments. For strongly complexing cations, the magnitude of the acquired effective charge was on the order of 1 cation per 100 monomer units. For monovalent cations, the relative strength of binding varies as Na+ < K+ ≈ Rb+ ≈ Cs+, whereas Li+ exhibited no significant binding. All polyvalent cations bind very weakly, except for Ba2+ that exhibited strong binding. Anions do not bind, as is shown by the lack of response to the chemical nature of anionic species (perchlorate, iodide, or acetate). Diffusion experiments directly show that the acetate anion with monovalent cations does not associate with PEO. Considering all cations, we find that the observed binding does not follow any Hofmeister order. Instead, binding occurs below a critical surface charge density, which indicates that the degree of complexation is defined by the solvation shell. A large solvation shell prevents the binding of most multivalent ions.

  • 144.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Meriguet, Guillaume
    Hallberg, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fang, Yuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stilbs, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ion association in aqueous and non-aqueous solutions probed by diffusion and electrophoretic NMR2015In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 5, p. 3402-3408Article in journal (Refereed)
    Abstract [en]

    The results of diffusion and electrophoretic NMR (eNMR) measurements are reported for a series of tetramethylammonium (TMA) electrolytes (with sulphate, fluoride, acetate, chloride, bromide, nitrate, iodide and perchlorate as anions) in deuterated solvents such as water, dimethylsulphoxide (DMSO), acetonitrile, methanol and ethanol. In addition, similar data are presented for aqueous solutions of tetraalkylammonium salts with increasing alkyl chain length. The combination of diffusion NMR and eNMR yields the effective charge for the TMA cation. Relative to the nominal charge of z(nom) = 1 of TMA, the effective charge in the different solvents is found to be progressively smaller in the order water > DMSO > methanol > acetonitrile > ethanol. A part of this observed trend is ascribed to regular ion-ion interactions incorporated in the Onsager limiting law. Indeed, in solvents with high dielectric constants such as water, DMSO and methanol, the Onsager limiting law describes well the observations for all tetraalkylammonium ions. For ethanol and acetonitrile, there is a significant difference between the experimental data and the expected limiting-law behavior that is attributed to ion association (ion pairing) not taken into consideration by the Onsager limiting law.

  • 145.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Mériguet, Guillaume
    Sorbonne Universités, UPMC Université Pierre et Marie Curie Paris 06 and CNRS.
    Hallberg, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stilbs, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ion association in aqueous and non-aqueous solutions probed by diffusion and electrophoretic NMRManuscript (preprint) (Other academic)
  • 146.
    Giesecke, Marianne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Szabo, Zoltan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    The protonation state and binding mode in a metal coordination complex from the charge measured in solution by electrophoretic NMR2013In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 5, no 7, p. 1648-1651Article in journal (Refereed)
    Abstract [en]

    We measured with high accuracy the effective charge of a uranium (VI)-AMP complex by electrophoretic NMR (eNMR). Using the same method, the degree of counterion association is also assessed which leads to a quantitative determination of the nominal charge which then provides the degree of ligand deprotonation in the complex. This demonstrates a new application of eNMR for resolving structural details of supramolecular complexes.

  • 147.
    Gu, Chungang
    et al.
    AstraZeneca, R&D Boston, Waltham, MA USA.;AstraZeneca, R&D Wilmington, Wilmington, DE USA..
    Lewis, Richard J.
    AstraZeneca, R&D Molndal, Molndal, Sweden.;AstraZeneca, R&D Charnwood, Loughborough, Leics, England..
    Wells, Andrew S.
    AstraZeneca, R&D Charnwood, Loughborough, Leics, England..
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. AstraZeneca, R&D Sodertalje, Sodertalje, Sweden.
    Hosagrahara, Vinayak P.
    AstraZeneca, R&D Boston, Waltham, MA USA..
    Johnsson, Eskil
    AstraZeneca, R&D Molndal, Molndal, Sweden.;AstraZeneca, R&D Lund, Lund, Sweden..
    Hallstrom, Gosta
    AstraZeneca, R&D Lund, Lund, Sweden..
    Lipid Peroxide-Mediated Oxidative Rearrangement of the Pyrazinone Carboxamide Core of Neutrophil Elastase Inhibitor AZD9819 in Blood Plasma Samples2015In: Drug Metabolism And Disposition, ISSN 0090-9556, E-ISSN 1521-009X, Vol. 43, no 10, p. 1441-1449Article in journal (Refereed)
    Abstract [en]

    This study focused on the mechanistic interpretation of ex vivo oxidation of a candidate drug in blood plasma samples. An unexpected lipid peroxide-mediated epoxidation followed by a dramatic rearrangement led to production of a five-membered oxazole derivative from the original six-membered pyrazinone-carboxamide core of a human neutrophil elastase inhibitor, 6-(1-(4-cyanophenyl)-1H-pyrazol-5-yl)-N-ethyl-5-methyl-3-oxo-4-(3-(trifluoromethyl) phenyl)-3,4-dihydropyrazine-2-carboxamide (AZD9819). The rearranged oxidation product 2-(1-(4-cyanophenyl)-1H-pyrazol-5-yl)-5-(N-ethylacetamido)-N-(3-(trifluoromethyl)phenyl)oxazole-4-carboxamide was characterized by accurate-mass tandem mass spectrometry fragmentations, by two-dimensional NMR and X-ray crystallography of an authentic standard, and by incorporation of an O-18 atom from molecular O-18(2) to the location predicted by our proposed mechanism. The lipid peroxide-mediated oxidation was demonstrated by using human low-density lipoprotein (LDL) in pH 7.4 phosphate buffer and by inhibiting the oxidation with ascorbic acid or L-glutathione, two antioxidants effective in both plasma and the LDL incubation. A nucleophilic mechanism for the epoxidation of AZD9819 by lipid hydroperoxides explains the prevention of its ex vivo oxidation by acidification of the plasma samples. The discovery of the lipid peroxide-dependent oxidation of an analyte and the means of prevention could provide valuable information for biotransformation and bioanalysis.

  • 148.
    Gustafsson, Jon Petter
    et al.
    Swedish University of Agricultural Sciences, Uppsala.
    Oromieh, Aidin Geranmayeh
    Swedish University of Agricultural Sciences, Uppsala.
    Sjöstedt, Carin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Persson, Ingmar
    Sveriges Lantbruksuniversitet.
    Berggren Kleja, Dan
    Swedish Geotechnical Institute, Stockholm, Sweden.
    Chromium (III) and bismuth (III) complexation to organic matter: EXAFS Spectroscopy and equilibrium modeling2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 5, p. 1235-Article in journal (Refereed)
    Abstract [en]

    The complexation of chromium(III) and bismuth(III) to organic matter was investigated by batch equilibrations with Suwannee River Fulvic Acid (SRFA) and with mor layer material (Risbergshöjden Oe). In the SRFA systems, 3 mM chromium(III) solutions were equilibrated with 9 g L-1 SRFA and equilibrated at different pH values ranging from 2 to 6. Characterization of the reaction products was made at MAX-Lab, Lund, Sweden, using Cr K-edge EXAFS spectroscopy at 5 989 eV. The spectra were interpreted using both conventional data treatment using EXAFSPAK and with wavelet transform (WT) analysis. The results show that chromium(III) formed monomeric organic complexes with SRFA. There was no evidence of polymerization with the exception of the particulate phase at pH 6, which was attributed to a limited extent of Cr(OH)3 formation.

    The mor layer material was equilibrated with chromium(III) and bismuth(III) solutions as a function of pH, time and competing ions (iron(III), aluminium(III), copper(II)). Again Cr

    K-edge and Bi L3-edge EXAFS spectroscopy was used, at 5 989 and 13 419 eV. The experiments showed a predominance of monomeric organic complexes for chromium(III). The sorption of chromium(III) was pH-dependent and to some extent found to be influenced by competition from aluminium(III) and copper(II). Chromium(III) complexation was found to be very slow at pH < 4, and equilibration times of three months or longer were required to reach equilibrium under these conditions. Concerning bismuth(III), complexation was quicker and found to be very strong, with more than 94 % bound at pH 1.2 at a high bismuth(III) loading. EXAFS spectroscopy showed that two complexes were involved, one monomeric and one di- or trimeric, with the latter being predominant at higher pH values, although it was present already at pH 1.2. In the organic bismuth(III) complexes, the bismuth(III) octahedron was found to be strongly distorted, which implies strong binding to organic acid functional groups. The complexation of bismuth(III) remained essentially unchanged even in the presence of a potent competitor such as iron(III).

    The results from the spectroscopic investigation and from the quantitative solution data were used to calibrate new and improved complexation models for the Stockholm Humic (SHM) and the NICA-Donnan models. In the case of the Stockholm Humic Model, both complexes as found by EXAFS spectroscopy were considered explicitly; this ensured the model to predict minimum competition effects in agreement with the laboratory results.

  • 149.
    Gustavsson, John
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Li, Gongzhuo
    Hummelgård, Christine
    Bäckström, Joakim
    Permascand AB.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions2012In: Journal of Electrochemical Science and Engineering, ISSN 1847-9286, Vol. 2, no 4, p. 155-169Article in journal (Refereed)
    Abstract [en]

    The goal of this study was to gain a better understanding of the feasibility of replacing Cr(VI) in the chlorate process by Mo(VI), focusing on the cathode reaction selectivity for hydrogen evolution on steel and titanium in a hypochlorite containing electrolyte. To evaluate the ability of Cr(VI) and Mo(VI) additions to hinder hypochlorite reduction, potential sweep experiments on rotating disc electrodes and cathodic current efficiency (CE) measurements on stationary electrodes were performed. Formed electrode films were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cathodic hypochlorite reduction is hindered by the Mo-containing films formed on the cathode surface after Mo(VI) addition to the electrolyte, but much less efficient compared to Cr(VI) addition. Very low levels of Cr(VI), in the mM range, can efficiently suppress hypochlorite reduction on polished titanium and steel. Phosphate does not negatively influence the CE in the presence of Cr(VI) or Mo(VI) but the Mo-containing cathode films become thinner if the electrolyte during the film build-up also contains phosphate. For a RuO2-TiO2 anode polarized in electrolyte with 40 mM Mo(VI), the anode potential increased and increased molybdenum levels were detected on the electrode surface.

  • 150. Hagfeldt, A.
    et al.
    Cappel, U. B.
    Boschloo, G.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pettersson, H.
    Gibson, E. A.
    Mesoporous dye-sensitized solar cells2012In: Reference Module in Earth Systems and Environmental Sciences, Elsevier, 2012, Vol. 1, p. 481-496Chapter in book (Other academic)
    Abstract [en]

    Photovoltaics, or solar cells, are fast growing both with regards to industrialization and research. Globally, the total PV installation is around 40 GW and an annual growth rate of 45% has been experienced over recent years. In the comparison between different photovoltaic technologies a figure of merit is the production cost per peak watt of solar electricity produced. For so called second generation thin film solar cells production costs down to and even below 1 $/W-1 peak are reported. To be competitive with conventional energy sources for large-scale electricity production new PV technologies need to aim at production costs below 0.5 $/W-1 peak. The dye-sensitized solar cell (DSC) is a molecular solar cell technology which have the potential to achieve production costs below 0.5 $/W-1 peak. DSC is based on molecular and nanometer-scale components. Record cell efficiencies of 12%, promising stability data and means of energy efficient production methods have been accomplished. As selling points for the DSC technology the prospect of low-cost investments and fabrication are key features. DSCs offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. This chapter describes the basic principles of the operation of DSC, the state-of-the-art, the materials development that is currently taking place as well as the potentials for future development.

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