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  • 1. Almeida, Roseley
    et al.
    Banerjee, Amitava
    Chakraborty, Sudip
    Almeida, Jailton
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Theoretical Evidence behind Bifunctional Catalytic Activity in Pristine and Functionalized Al2C Monolayers2018In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 1, p. 148-152Article in journal (Refereed)
    Abstract [en]

    First principles electronic structure calculations based on the density functional theory (DFT) framework are performed to investigate hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on two-dimensional Al2C monolayers. In addition to the pristine Al2C monolayer, monolayers doped with Nitrogen (N), Phosphorous (P), Boron (B), and Sulphur (S) are also investigated. After determining the individual adsorption energy of hydrogen and oxygen on the different functionalized Al2C monolayers, the adsorption free energies are predicted for each of the functionalized monolayers in order to assess their suitability for HER or OER. The density of states and optical absorption spectra calculations along with the work function of the functionalized Al2C monolayers enable us to gain a profound understanding of the electronic structure for the individual system and their relation to the water splitting mechanism.

  • 2.
    Alniss, Hasan Y.
    et al.
    Univ Sharjah, Coll Pharm, POB 27272, Sharjah, U Arab Emirates.;Univ Sharjah, Sharjah Inst Med Res, POB 27272, Sharjah, U Arab Emirates..
    Witzel, Ini-Isabee
    New York Univ Abu Dhabi, Core Technol Platform, POB 129188, Abu Dhabi, U Arab Emirates..
    Semreen, Mohammad H.
    Univ Sharjah, Coll Pharm, POB 27272, Sharjah, U Arab Emirates.;Univ Sharjah, Sharjah Inst Med Res, POB 27272, Sharjah, U Arab Emirates..
    Panda, Pritam Kumar
    Uppsala Univ, Dept Phys & Astron, D,Box 516, SE-75120 Uppsala, Sweden..
    Mishra, Yogendra Kumar
    Univ Kiel, Inst Mat Sci, Funct Nanomat, Kaiserstr 2, D-24143 Kiel, Germany.;Univ Southern Denmark, NanoSYD, Mads Clausen Inst, Alsion 2, DK-6400 Sonderborg, Denmark..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Parkinson, John A.
    Univ Strathclyde, Dept Pure & Appl Chem, WestCHEM, 295 Cathedral St, Glasgow G1 1XL, Lanark, Scotland..
    Investigation of the Factors That Dictate the Preferred Orientation of Lexitropsins in the Minor Groove of DNA2019In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 62, no 22, p. 10423-10440Article in journal (Refereed)
    Abstract [en]

    Lexitropsins are small molecules that bind to the minor groove of DNA as antiparallel dimers in a specific orientation. These molecules have shown therapeutic potential in the treatment of several diseases; however, the development of these molecules to target particular genes requires revealing the factors that dictate their preferred orientation in the minor grooves, which to date have not been investigated. In this study, a distinct structure (thzC) was carefully designed as an analog of a well-characterized lexitropsin (thzA) to reveal the factors that dictate the preferred binding orientation. Comparative evaluations of the biophysical and molecular modeling results of both compounds showed that the position of the dimethylaminopropyl group and the orientation of the amide links of the ligand with respect to the 5'-3'-ends; dictate the preferred orientation of lexitropsins in the minor grooves. These findings could be useful in the design of novel lexitropsins to selectively target specific genes.

  • 3.
    Alniss, Hasan Y.
    et al.
    Univ Sharjah, Coll Pharm, POB 27272, Sharjah, U Arab Emirates.;Univ Sharjah, Sharjah Inst Med Res, POB 27272, Sharjah, U Arab Emirates..
    Witzel, Ini-Isabee
    New York Univ Abu Dhabi, Core Technol Platform, POB 129188, Abu Dhabi, U Arab Emirates..
    Semreen, Mohammad H.
    Univ Sharjah, Coll Pharm, POB 27272, Sharjah, U Arab Emirates.;Univ Sharjah, Sharjah Inst Med Res, POB 27272, Sharjah, U Arab Emirates..
    Panda, Pritam Kumar
    Uppsala Univ, Dept Phys & Astron, D,Box 516, SE-75120 Uppsala, Sweden..
    Mishra, Yogendra Kumar
    Univ Kiel, Inst Mat Sci, Funct Nanomat, Kaiserstr 2, D-24143 Kiel, Germany.;Univ Southern Denmark, NanoSYD, Mads Clausen Inst, Alsion 2, DK-6400 Sonderborg, Denmark..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Parkinson, John A.
    Univ Strathclyde, Dept Pure & Appl Chem, WestCHEM, 295 Cathedral St, Glasgow G1 1XL, Lanark, Scotland..
    Investigation of the Factors That Dictate the Preferred Orientation of Lexitropsins in the Minor Groove of DNA2019In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 62, no 22, p. 10423-10440Article in journal (Refereed)
    Abstract [en]

    Lexitropsins are small molecules that bind to the minor groove of DNA as antiparallel dimers in a specific orientation. These molecules have shown therapeutic potential in the treatment of several diseases; however, the development of these molecules to target particular genes requires revealing the factors that dictate their preferred orientation in the minor grooves, which to date have not been investigated. In this study, a distinct structure (thzC) was carefully designed as an analog of a well-characterized lexitropsin (thzA) to reveal the factors that dictate the preferred binding orientation. Comparative evaluations of the biophysical and molecular modeling results of both compounds showed that the position of the dimethylaminopropyl group and the orientation of the amide links of the ligand with respect to the 5'-3'-ends; dictate the preferred orientation of lexitropsins in the minor grooves. These findings could be useful in the design of novel lexitropsins to selectively target specific genes.

  • 4.
    Anikina, Ekaterina
    et al.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Box 516, S-75120 Uppsala, Sweden.;South Ural State Univ, Inst Nat Sci & Math, 76 Lenin Prospekt, Chelyabinsk 454080, Russia..
    Banerjee, Amitava
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. KTH Royal Inst Technol, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Beskachko, Valery
    South Ural State Univ, Inst Nat Sci & Math, 76 Lenin Prospekt, Chelyabinsk 454080, Russia..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Box 516, S-75120 Uppsala, Sweden.;KTH Royal Inst Technol, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Li-Functionalized Carbon Nanotubes for Hydrogen Storage: Importance of Size Effects2019In: ACS APPLIED NANO MATERIALS, ISSN 2574-0970, Vol. 2, no 5, p. 3021-3030Article in journal (Refereed)
    Abstract [en]

    We investigated Li-doped carbon nanotubes (CNTs) as a promising hydrogen storage media. In this computational model, we considered isolated lithium atom adsorbed on a CNT wall as an adsorption site for hydrogen. We focused on the influence of size effects on the structural and energetic characteristics of CNT(n,n)@Li+kH(2) complexes where n = 5, 7, 9; k = 1,..., 6; N, = 4, 5, 6 (N-c is translation length of CNT, expressed in terms of a number of CNT unit cells). We proved that modeled CNT length substantially influences internal sorption of Li and hydrogen on the narrow tube (5,5), which subsequently alters the adsorption energies of H-2 molecules and causes the deformation of the carbon framework. Moreover, the size effects are not pronounced in the case of external sorption for all considered CNT translation lengths and diameters. We have not observed any noticeable qualitative difference between internal and external hydrogen sorption in the nanotube wider than CNT(5,5). In the case of external adsorption on all considered nanotubes, doping with Li increases hydrogen adsorption energies of up to four H-2 molecules by 100 meV in comparison with pure CNTs. And the local density approximation estimations (similar to 250 meV/H-2) of adsorption energy on Li-decorated CNTs exceed the lowest requirement proposed by the U.S. Department of Energy (200 meV/H-2). In the case of internal sorption on Li-functionalized tubes, the generalized gradient approximation also gives hydrogen adsorption energies in the desired range of 200-600 meV/H-2. However, steric hindrances could prevent sufficient hydrogen uptakes (less than 2 wt % inside CNT(5,5)). We believe that our findings on the size effects are important for estimation of CNT's hydrogen storage properties.

  • 5. Araujo, Rafael B.
    et al.
    Banerjee, Amitava
    Panigrahi, Puspamitra
    Yang, Li
    Sjodin, Martin
    Stromme, Maria
    Araujo, C. Moyses
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Sweden.
    Assessing the electrochemical properties of polypyridine and polythiophene for prospective applications in sustainable organic batteries2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 4, p. 3307-3314Article in journal (Refereed)
    Abstract [en]

    Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, the key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.

  • 6. Araujo, Rafael B.
    et al.
    Banerjee, Amitava
    Panigrahi, Puspamitra
    Yang, Li
    Stromme, Maria
    Sjodin, Martin
    Araujo, C. Moyses
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Designing strategies to tune reduction potential of organic molecules for sustainable high capacity battery application2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4430-4454Article in journal (Refereed)
    Abstract [en]

    Organic compounds evolve as a promising alternative to currently used inorganic materials in rechargeable batteries due to their low-cost, environmental friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of the density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, and pi bonds, as well as carboxyl groups on the formal potential, have been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.

  • 7. Banerjee, A.
    et al.
    Araujo, R. B.
    Sjödin, M.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Identifying the tuning key of disproportionation redox reaction in terephthalate: A Li-based anode for sustainable organic batteries2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 47, p. 301-308Article in journal (Refereed)
    Abstract [en]

    The ever-increasing consumption of energy storage devices has pushed the scientific community to realize strategies toward organic electrodes with superior properties. This is owed to advantages such as economic viability and eco-friendliness. In this context, the family of conjugated dicarboxylates has emerged as an interesting candidate for the application as negative electrodes in advanced Li-ion batteries due to the revealed thermal stability, rate capability, high capacity and high cyclability. This work aims to rationalize the effects of small molecular modifications on the electrochemical properties of the terephthalate anode by means of first principles calculations. The crystal structure prediction of the investigated host compounds dilithium terephthalate (Li2TP) and diethyl terephthalate (Et2Li0TP) together with their crystal modification upon battery cycling enable us to calculate the potential profile of these materials. Distinct underlying mechanisms of the redox reactions were obtained where Li2TP comes with a disproportionation reaction while Et2Li0TP displays sequential redox reactions. This effect proved to be strongly correlated to the Li coordination number evolution upon the Li insertion into the host structures. Finally, the calculations of sublimation enthalpy inferred that polymerization techniques could easily be employed in Et2Li0TP as compared to Li2TP. Similar results are observed with methyl, propyl, and vinyl capped groups. That could be a strategy to enhance the properties of this compound placing it into the gallery of the new anode materials for state of art Li-batteries.

  • 8. Banerjee, Amitava
    et al.
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Bromination-induced stability enhancement with a multivalley optical response signature in guanidinium [C(NH2)(3)](+)-based hybrid perovskite solar cells2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 35, p. 18561-18568Article in journal (Refereed)
    Abstract [en]

    Guanidinium lead iodide (GAPbI(3)) has been synthesized experimentally, but stability remains an issue, which can be modulated by the insertion of bromine (Br) into the system. We have performed a systematic theoretical investigation to see how bromination can tune the stability of GAPbI(3). The optical properties were also determined, and we have found formation enthalpy-based stability in the perovskite systems, which are active in the visible and IR region even after bromine insertion and additionally more active in the IR range with the transition from GAPbI(3) to GAPbBr(3). The spin orbit coupling effect is considered throughout the band structure calculations. The ensemble of the primary and secondary gaps in the half and fully brominated hybrid perovskites leads to the phenomenon of a multipeak response in the optical spectra, which can be subsequently attributed as multivalley optical response behaviour. This multivalley optical behaviour enables the brominated guanidinium-based hybrid perovskites to exhibit broad light harvesting abilities, and this can be perceived as an idea for natural multi-junction solar cells.

  • 9.
    Banerjee, Amitava
    et al.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Chakraborty, Sudip
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Jena, Naresh K.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Scrupulous Probing of Bifunctional Catalytic Activity of Borophene Monolayer: Mapping Reaction Coordinate with Charge Transfer2018In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 8, p. 3571-3576Article in journal (Refereed)
    Abstract [en]

    We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on two-dimensional (2D) noble metal free borophene monolayer based on first-principles electronic structure calculations. We have investigated the effect of Ti functionalization on borophene monolayer from the perspective of HER and OER activities enhancement. We have probed the activities based on the reaction coordinate, which is conceptually related to the adsorption free energies of the intermediates of HER and OER, as well as from the vibrational frequency analysis with the corresponding charge transfer mechanism between the surface and the adsorbate. Tifunctionalized borophene has emerged as a promising material for HER and OER mechanisms. We believe that our probing method, based on reaction coordinate coupled with vibrational analysis that has been validated by the charge transfer mechanism, would certainly become as a robust prediction route for HER and OER mechanisms in coming days.

  • 10.
    Bovornratanaraks, Thiti
    et al.
    Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL, Bangkok 10330, Thailand.;Chulalongkorn Univ, Fac Sci, Dept Phys, PEMRU, Bangkok 10330, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Tsuppayakorn-aek, Prutthipong
    Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL, Bangkok 10330, Thailand.;Chulalongkorn Univ, Fac Sci, Dept Phys, PEMRU, Bangkok 10330, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Luo, Wei
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Ground-state structure of semiconducting and superconducting phases in xenon carbides at high pressure2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 2459Article in journal (Refereed)
    Abstract [en]

    The 'missing Xe paradox' is one of the phenomena at the Earth's atmosphere. Studying the 'missing Xe paradox' will provide insights into a chemical reaction of Xe with C. We search the ground-state structure candidates of xenon carbides using the Universal Structure Predictor: Evolutionary Xtallography (USPEX) code, which has been successfully applied to a variety of systems. We predict that XeC2 is the most stable among the convex hull. We find that the I((4) over bar)2m structure of XeC2 is the semiconducting phase. Accurate electronic structures of tetragonal XeC2 have been calculated using a hybrid density functionals HSE06, which gives larger more accurate band gap than a GGA-PBE exchange-correlation functional. Specifically, we find that the I((4) over bar)2m structure of XeC2 is a dynamically stable structure at high pressure. We also predict that the P6/mmm structure of XeC2 is the superconducting phase with a critical temperature of 38 K at 200 GPa. The ground-state structure of xenon carbides is of critical importance for understanding in the missing Xe. We discuss the inference of the stable structures of XeC2. The accumulation of electrons between Xe and C led to the stability by investigating electron localization function (ELF).

  • 11.
    Chakraborty, Sudip
    et al.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Banerjee, Amitava
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Watcharatharapong, Teeraphat
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Araujo, Rafael B.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden.
    Current computational trends in polyanionic cathode materials for Li and Na batteries2018In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 30, no 28, article id 283003Article, review/survey (Refereed)
    Abstract [en]

    A long-standing effort has been devoted for the development of high energy density cathodes both for Li-and Na-ion batteries (LIBs and SIBs). The scientific communities in battery research primarily divide the Li- and Na-ion cathode materials into two categories: layered oxides and polyanionic compounds. Researchers are trying to improve the energy density of such materials through materials screening by mixing the transition metals or changing the concentration of Li or Na in the polyanionic compounds. Due to the fact that there is more stability in the polyanionic frameworks, batteries based on these materials mostly provide a prolonged cycling life as compared to the layered oxide materials. Nevertheless, the bottleneck for such compounds is the weight penalty from polyanionic groups that results into the lower capacity. The anion engineering could be considered as an essential way out to design such polyanionic compounds to resolve this issue and to fetch improved cathode performance. In this topical review we present a systematic overview of the polyanionic cathode materials used for LIBs and SIBs. We will also present the computational methodologies that have become significantly relevant for battery research. We will make an attempt to provide the theoretical insight with a current development in sulfate (SO4), silicate (SiO4) and phosphate (PO4) based cathode materials for LIBs and SIBs. We will end this topical review with the future outlook, that will consist of the next generation organic electrode materials, mainly based on conjugated carbonyl compounds.

  • 12. Das, Suman
    et al.
    Swain, Diptikanta
    Araujo, Rafael B.
    Shi, Songxin
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Row, Tayur N. Guru
    Bhattacharyya, Aninda J.
    Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries2018In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 13, no 3, p. 299-310Article in journal (Refereed)
    Abstract [en]

    We discuss here a unique flexible non-carbonaceous layered host, namely, metal titanium niobates (M-Ti-niobate, M: Al3+, Pb2+, Sb3+, Ba2+, Mg2+), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M-Ti-niobate is formed by ion exchange of the K+ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO6 and NbO6 octahedral units in the sol-gel synthesized potassium titanium niobate (KTiNbO5). Drastic volume changes (approximately 300-400%) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M-Ti-niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50-75% of total K+) in the M-Ti-niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M-Ti-niobate can be cycled over a wide voltage range (as low as 0.01V) and displays remarkably stable Li+ and Na+ ion cyclability (>2 Li+/Na+ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al-titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M-Ti-niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.

  • 13.
    Das, Tisita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India.
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.
    Das, Gour P.
    Functionalization and Defect-Driven Water Splitting Mechanism on a Quasi-Two-Dimensional TiO2 Hexagonal Nanosheet2019In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 2, no 7, p. 5074-5082Article in journal (Refereed)
    Abstract [en]

    In this work, we have dealt with the functionalization of a newly reported quasi-2D hexagonal nanosheet (HNS) of titanium dioxide (TiO2) for photocatalytic water splitting to generate hydrogen and oxygen. Functionalization has been carried out by creating a single oxygen vacancy defect as well as by incorporating substitutional doping with C, N, P, and S atoms at the O site of TiO2 HNS. The effects of functionalization and vacancy defects on the structural and electronic properties of HNS have been investigated by determining the corresponding projected density of states. It has been observed that functionalization causes a shift in the VBM and CBM of HNS, which in principle influences the catalytic activity. In addition, we have determined the work function for these materials in order to correlate them with the electrochemical activities of different considered HNSs. The catalytic activity has been predicted by determining the reaction coordinate as constructed from the free energies of the different reaction intermediates involved in HER and OER Among all of the systems that we have studied, HNS with an oxygen monovacancy has emerged as the best possible candidate for the water-splitting mechanism.

  • 14.
    Das, Tisita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    Chakraborty, Sudip
    Uppsala Univ, Condensed Matter Theory Grp, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Das, Gour P.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    TiS2 Monolayer as an Emerging Ultrathin Bifunctional Catalyst: Influence of Defects and Functionalization2019In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 20, no 4, p. 608-617Article in journal (Refereed)
    Abstract [en]

    We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two-dimensional (2D) noble-metal-free titanium disulfide (TiS2) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS2 is based on electronic-structure calculations witihin the framework of density functional theory (DFT). Since TiS2 is the lightest compound among the group-IV TMDCs, it is worth exploring the catalytic activity of a TiS2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS2 monolayer by determining the density of states, work-function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects.

  • 15. Djouambi, Nadia
    et al.
    Bougheloum, Chafika
    Messalhi, Abdelrani
    Bououdina, Mohamed
    Banerjee, Amitava
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    New Concept on Photocatalytic Degradation of Thiophene Derivatives: Experimental and DFT Studies2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 27, p. 15646-15651Article in journal (Refereed)
    Abstract [en]

    In this study, the photocatalytic degradation of seven sulfur compounds (2-methylthiophene, 3-methylthiophene, 2-phenylthiophene, 3-phenylthiophene, 2,5-diphenylthiophene, 2-(2-thienyl) pyridine, and 2-(3-thienyl) pyridine in semiaqueous medium are compared to thiophene. The apparent-reaction-rate constant (k) is found to decrease in the following order: 2,5-diphenylthiophene > 2-(2-thienyl) pyridine > 2-penhylthiophene methylthiophene > 3-penhylthiophene > 2-methylthiophene > 2-(3-thienyl) pyridine > 3-thiophene. From the data obtained by UV light absorption (lambda(max)) measurements and electronic structure calculations (frontier orbitals energy, global hardness, and global softness), the kinetic parameters of the reaction have been determined. Among the studied compounds, thiophene with a high lambda(max) and low calculated LUMO-HOMO gap energy has showed higher activity under UV irradiation. Interestingly, a lower activity is observed with low lambda(max) and high LUMO-HOMO gap energy. This demonstrates, for the first time, that the reactivity depends essentially on the thermodynamic stability of the sulfur compound rather than on the nature or the position of the substituent on the ring.

  • 16. Hussain, T.
    et al.
    Kaewmaraya, T.
    Chakraborty, S.
    Vovusha, H.
    Amornkitbamrung, V.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division (PSE), Thuwal, Saudi Arabia.
    Defected and Functionalized Germanene-based Nanosensors under Sulfur Comprising Gas Exposure2018In: ACS Sensors, ISSN 2379-3694, Vol. 3, no 4, p. 867-874Article in journal (Refereed)
    Abstract [en]

    Efficient sensing of sulfur containing toxic gases like H2S and SO2 is of the utmost importance due to the adverse effects of these noxious gases. Absence of an efficient 2D-based nanosensor capable of anchoring H2S and SO2 with feasible binding and an apparent variation in electronic properties upon the exposure of gas molecules has motivated us to explore the promise of a germanene nanosheet (Ge-NS) for this purpose. In the present study, we have performed a comprehensive computational investigation by means of DFT-based first-principles calculations to envisage the structural, electronic, and gas sensing properties of pristine, defected, and metal substituted Ge-NSs. Our initial screening has revealed that although interaction of SO2 with pristine Ge-NSs is within the desirable range, H2S binding however falls below the required values to guarantee an effective sensing. To improve the binding characteristics, we have considered the interactions between H2S and SO2 with defected and metal substituted Ge-NS. The systematic removals of Ge atoms from a reasonably large super cell lead to monovacancy, divacancies, and trivacancies in Ge-NS. Similarly, different transition metals like As, Co, Cu, Fe, Ga, Ge, Ni, and Zn have been substituted into the monolayer to realize substituted Ge-NS. Our van der Waals corrected DFT calculations have concluded that the vacancy and substitution defects not only improve the binding characteristics but also enhance the sensing propensity of both H2S and SO2. The total and projected density of states show significant variations in electronic properties of pristine and defected Ge-NSs before and after the exposure to the gases, which are essential in constituting a signal to be detected by the external circuit of the sensor. We strongly believe that our present work would not only advance the knowledge towards the application of Ge-NS-based sensing but also provide motivation for the synthesis of such efficient nanosensor for H2S and SO2 based on Ge monolayer.

  • 17.
    Hussain, T.
    et al.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia.;Univ Queensland, Ctr Theoret & Computat Mol Sci, Australian Inst Bioengn & Nanotechnol, Brisbane, Qld 4072, Australia..
    Vovusha, H.
    KAUST, Phys Sci & Engn Div PSE, Thuwal 239556900, Saudi Arabia..
    Kaewmaraya, T.
    Khon Kaen Univ, Integrated Nanotechnol Res Ctr, Dept Phys, Khon Kaen, Thailand..
    Karton, A.
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Amornkitbamrung, V
    Khon Kaen Univ, Integrated Nanotechnol Res Ctr, Dept Phys, Khon Kaen, Thailand..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.
    Graphitic carbon nitride nano sheets functionalized with selected transition metal dopants: an efficient way to store CO22018In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 29, no 41, article id 415502Article in journal (Refereed)
    Abstract [en]

    Proficient capture of carbon dioxide (CO2) is considered to be a backbone for environment protection through countering the climate change caused by mounting carbon content. Here we present a comprehensive mechanism to design novel functional nanostructures capable of capturing a large amount of CO2 efficiently. By means of van der Waals corrected density functional theory calculations, we have studied the structural, electronic and CO2 storage properties of carbon nitride (g-C6N8) nano sheets functionalized with a range of transition metal (TM) dopants ranging from Sc to Zn. The considered TMs bind strongly to the nano sheets with binding energies exceeding their respective cohesive energies, thus abolishing the possibility of metal cluster formation. Uniformly dispersed TMs change the electronic properties of semiconducting g-C6N8 through the transfer of valence charges from the former to the latter. This leaves all the TM dopants with significant positive charges, which are beneficial for CO2 adsorption. We have found that each TM's dopants anchor a maximum of four CO2 molecules with suitable adsorption energies (-0.15 to -1.0 eV) for ambient condition applications. Thus g-C6N8 nano sheets functionalized with selected TMs could serve as an ideal sorbent for CO2 capture.

  • 18.
    Hussain, T.
    et al.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia.;Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Vovusha, H.
    KAUST, Phys Sci & Engn Div PSE, Thuwal 239556900, Saudi Arabia.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Umer, R.
    Univ Southern Queensland, Ctr Future Mat, Toowoomba, Qld 4350, Australia..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Superior sensing affinities of acetone towards vacancy induced and metallized ZnO monolayers2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 456, p. 711-716Article in journal (Refereed)
    Abstract [en]

    The sensing propensities of acetone molecule towards zinc oxide monolayers (ZnO-ML) have been studied by means of density functional theory (DFT) calculations. Our van der Waals induced first principles calculations revealed that pristine ZnO-ML barely binds acetone, which limits its application as acetone sensing materials. However the formation of vacancies and foreign element doping improves acetone binding drastically. Among several defects, divacancy, and metal doping Li, Sc and Ti functionalization on ZnO-ML has been found the most promising ones. Presence of dangling electrons and partial positive charges in case of vacancy-induced and metallized ZnO-ML respectively, is believed to enhance the binding of acetone on the monolayers. The acetone-ZnO binding behavior has been further explained through studying the electronic properties by density of states and charge transfer mechanism though Bader analysis. Thus defected and metallized ZnO-ML could be a promising nano sensor for efficient sensing/capture of acetone.

  • 19. Hussain, Tanveer
    et al.
    Kaewmaraya, Thanayut
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Defect and Substitution-Induced Silicene Sensor to Probe Toxic Gases2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 44, p. 25256-25262Article in journal (Refereed)
    Abstract [en]

    Structural, electronic, and gas-sensing properties of pure, defected, and substituted silicene monolayer have been studied using first-principles calculations based on density functional theory. The spin-polarized calculations with van der Waals effect taken into consideration have revealed that the pristine silicene sheet rarely adsorbs the CO2, H2S, and SO2 gas molecules, which restricts the gas-sensing application of this 2D material. However, inducing vacancy defect in silicene drastically changes the electronic properties, and as a consequence it also improves the binding of exposed gas molecules significantly. Our Bader charge analysis reveals that a considerable amount of charge is being transferred from the defected silicene to the gases, resulting in binding energy improvement between silicene and the gas molecules. The change in binding energies has further been explained by plotting density of states. In addition to the vacancy defects, we have also considered the substitution of Al, B, N, and S in silicene. We found that the sensing propensity of silicene is more sensitive to the vacancy defect, as compared with the impurities.

  • 20. Hussain, Tanveer
    et al.
    Vovusha, Hakkim
    Kaewmaraya, Thanayut
    Amornkitbamrung, Vittaya
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Adsorption characteristics of DNA nucleobases, aromatic amino acids and heterocyclic molecules on silicene and germanene monolayers2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 255, p. 2713-2720Article in journal (Refereed)
    Abstract [en]

    Binding of DNA/RNA nucleobases, aromatic amino acids and heterocyclic molecules on two-dimensional silicene and germanene sheets have been investigated for the application of sensing of biomolecules using first principle density functional theory calculations. Binding energy range for nucleobases, amino acids and heterocyclic molecules with both the sheets have been found to be (0.43-1.16 eV), (0.70-1.58 eV) and (0.22-0.96 eV) respectively, which along with the binding distances show that these molecules bind to both sheets by physisorption and chemisorption process. The exchange of electric charges between the monolayers and the incident molecules has been examined by means of Bader charge analysis. It has been observed that the introduction of DNA/RNA nucleobases, aromatic amino acids and heterocyclic molecules alters the electronic properties of both silicene and germanene nano sheets as studied by plotting the total (TDOS) and partial (PDOS) density of states. The DOS plots reveal the variation in the band gaps of both silicene and germanene caused by the introduction of studied molecules. Based on the obtained results we suggest that both silicene and germanene monolayers in their pristine form could be useful for sensing of biomolecules.

  • 21.
    Jimlim, Pornmongkol
    et al.
    Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL,Phys Energy Mat Res Unit, Bangkok 10330, Thailand.;Mahidol Wittayanusorn Sch, Dept Phys, Nakhon Pathom 73170, Thailand..
    Kotmool, Komsilp
    Mahidol Wittayanusorn Sch, Dept Phys, Nakhon Pathom 73170, Thailand..
    Pinsook, Udomsilp
    Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL,Phys Energy Mat Res Unit, Bangkok 10330, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, Bangkok 10400, Thailand..
    Assabumrungrat, Suttichai
    Chulalongkorn Univ, Dept Chem Engn, Ctr Excellence Catalysis & Catalyt React Engn, Bangkok 10330, Thailand..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.
    Bovornratanaraks, Thiti
    Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL,Phys Energy Mat Res Unit, Bangkok 10330, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, Bangkok 10400, Thailand..
    Theoretical aspects in structural distortion and the electronic properties of lithium peroxide under high pressure2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 14, p. 9488-9497Article in journal (Refereed)
    Abstract [en]

    The structural phase transition and electronic properties of Li2O2 under pressures up to 500 GPa have been investigated using first-principles calculations. Two new structural phase transitions have been proposed at pressures around 75 GPa from the P6(3)/mmc structure to the P2(1) structure and around 136 GPa from the P2(1) structure to the P2(1)/c structure. The calculated phonon spectra have confirmed the dynamical stability of these structures. The pressure dependence of the lattice dynamics, O-O bond length, and band gaps in Li2O2 have also been reported. The band gaps of the P6(3)/mmc, P2(1), and P2(1)/c structures calculated by PBE and HSE06 have shown increasing trends with increasing pressure. Interestingly, the P6(3)/mmc band gap and c/a ratio have significantly decreased with the increasing O-O bond length and ELF value around 11 and 40 GPa. At these pressures, the phonon frequency of the O-O stretching modes has softened. This finding reveals the effects of structural distortion in three phases of Li2O2. Our study provides structural understanding and the electronic properties of Li2O2 under high pressure, which might be useful for investigating the charge transport through Li2O2 in lithium-air batteries and CO2 capture.

  • 22.
    Johansson, Malin B.
    et al.
    Uppsala Univ, Dept Chem, Div Phys Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Philippe, Bertrand
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, SE-75120 Uppsala, Sweden..
    Banerjee, Amitava
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Phuyal, Dibya
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, SE-75120 Uppsala, Sweden..
    Mukherjee, Soham
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, SE-75120 Uppsala, Sweden..
    Chakraborty, Sudip
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Cameau, Mathis
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, SE-75120 Uppsala, Sweden..
    Zhu, Huimin
    Uppsala Univ, Dept Chem, Div Phys Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Boschloo, Gerrit
    Uppsala Univ, Dept Chem, Div Phys Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Rensmo, Hakan
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, SE-75120 Uppsala, Sweden..
    Johansson, Erik M. J.
    Uppsala Univ, Dept Chem, Div Phys Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Cesium Bismuth Iodide Solar Cells from Systematic Molar Ratio Variation of CsI and BiI32019In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 18, p. 12040-12052Article in journal (Refereed)
    Abstract [en]

    Metal halide compounds with photovoltaic properties prepared from solution have received increased attention for utilization in solar cells. In this work, low-toxicity cesium bismuth iodides are synthesized from solution, and their photovoltaic and, optical properties as well as electronic and crystal structures are investigated. The X-ray diffraction patterns reveal that a CsI/BiI3 precursor ratio of 1.5:1 can convert pure rhombohedral BiI3 to pure hexagonal Cs3Bi2I9, but any ratio intermediate of this stoichiometry and pure BiI3 yields a mixture containing the two crystalline phases Cs3Bi2I9 and BiI3, with their relative fraction depending on the CsI/BiI3 ratio. Solar cells from the series of compounds are characterized, showing the highest efficiency for the compounds with a mixture of the two structures. The energies of the valence band edge were estimated using hard and soft X-ray photoelectron spectroscopy for more bulk and surface electronic properties, respectively. On the basis of these measurements, together with UV-vis-near-IR spectrophotometry, measuring the band gap, and Kelvin probe measurements for estimating the work function, an approximate energy diagram has been compiled clarifying the relationship between the positions of the valence and conduction band edges and the Fermi level.

  • 23.
    Khossossi, Nabil
    et al.
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, S-75120 Uppsala, Sweden..
    Banerjee, Amitava
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Benhouria, Younes
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Essaoudi, Ismail
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, S-75120 Uppsala, Sweden..
    Ainane, Abdelmajid
    Moulay Ismail Univ, Fac Sci, Dept Phys, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, S-75120 Uppsala, Sweden.;Max Planck Inst Phys Complexer Syst, NothnitzerStr 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, S-75120 Uppsala, Sweden..
    Ab initio study of a 2D h-BAs monolayer: a promising anode material for alkali-metal ion batteries2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 33, p. 18328-18337Article in journal (Refereed)
    Abstract [en]

    The selection of a suitable two dimensional anode material is one of the key steps in the development of alkali metal ion batteries to achieve superior performance with an ultrahigh rate of charging/discharging capability. Here, we have used state of the art density functional theory (DFT) to explore the feasibility of two dimensional (2D) honeycomb boron arsenide (h-BAs) as a potential anode for alkali-metal (Li/Na/K)-ion batteries. The structural and dynamic stability has been confirmed from the formation energy and the non-negative phonon frequency. The h-BAs monolayer exhibits negative adsorption-energy values of -0.422, -0.321 and -0.814 eV, for the Li, Na, and K-ions, respectively. Subsequently, during the charging process the adsorption-energy increases considerably without an energy-barrier when any of the A-atoms achieve a crucial distance (similar to 8 angstrom). In addition, it has been observed that insertion of the mono alkali metal atom into the h-BAs surface results in the semi-conducting nature of the monolayer being transformed into a metallic-state. The low energy barriers for Li (0.522 eV), Na (0.248), and K (0.204 eV) active ion migration imply high diffusion over the h-BAs surface, hence suggesting it has a high charge/discharge capability. Moreover, we have obtained low average operating voltages of 0.49 V (Li), 0.35 V (Na) and 0.26 V (K) and high theoretical capacities of 522.08 mA h g(-1) (for Li and Na) and 209.46 mA h g(-1) (for K) in this study. The aforementioned findings indicate that a h-BAs monolayer could be a promising anode material in the search for low cost and high performance alkali metal ion batteries.

  • 24.
    Klaa, Kaltoum
    et al.
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria.;Badji Mokhtar Univ, Dept Phys, LEREC Lab, Annaba, Algeria..
    Labidi, Salima
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria..
    Banerjee, Amitava
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Chakraborty, Sudip
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Labidi, Malika
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria..
    Amara, Abdelaziz
    Badji Mokhtar Univ, Dept Phys, LEREC Lab, Annaba, Algeria..
    Bououdina, Mohamed
    Univ Bahrain, Coll Sci, Dept Phys, POB Box 32038, Zallaq, Bahrain..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Composition dependent tuning of electronic and magnetic properties in transition metal substituted Rock-salt MgO2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 475, p. 44-53Article in journal (Refereed)
    Abstract [en]

    Full potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT) is used to investigate the structural, electronic and magnetic properties of Fe and Ni (3d transition metal) substituted Rock-salt wide band gap insulator Mg1-xMxO (M = Fe, Ni). We have performed spin polarized calculations throughout this work with generalized gradient approximation (GGA) type exchange correlation functional. Additionally, the electronic structures and density of states are computed using modified Becke-Johnson (mBJ) potential based approximation with the inclusion of coulomb energy (U = 7 eV). Based on the Vegard's law and structural optimization, the lattice parameter and bulk modulus are found to be in good agreement with experimental values. Moreover, the analysis of electronic band structures reveals an insulating character for Ni substituted MgO while semiconducting and half-metallic character for Fe substituted case. It has been found that the p-d super-exchange interaction provides a ferromagnetic character due to the 3d transition metal impurities and oxygen atom. The observed p-d hybridization at the top of the valence band edge in this investigations could be useful for magneto-optic and spintronic applications.

  • 25. Kotmool, K.
    et al.
    Li, B.
    Chakraborty, S.
    Bovornratanaraks, T.
    Luo, W.
    Mao, H. -K
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Sweden.
    High pressure-induced distortion in face-centered cubic phase of thallium2016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 40, p. 11143-11147Article in journal (Refereed)
    Abstract [en]

    The complex and unusual high-pressure phase transition of III-A (i.e. Al, Ga, and In) metals have been investigated in the last several decades because of their interesting periodic table position between the elements having metallic and covalent bonding. Our present first principles-based electronic structure calculations and experimental investigation have revealed the unusual distortion in face-centered cubic (f.c.c.) phase of the heavy element thallium (Tl) induced by the high pressure. We have predicted body-centered tetragonal (b.c.t) phase at 83 GPa using an evolutionary algorithm coupled with ab initio calculations, and this prediction has been confirmed with a slightly distorted parameter (√2 x a - c)/c lowered by 1% using an angle-dispersive X-ray diffraction technique. The density functional theory (DFT)-based calculations suggest that s-p mixing states and the valence-core overlapping of 6s and 5d states play the most important roles for the phase transitions along the pathway h.c.p → f.c.c. → b.c.t.

  • 26. Kotmool, Komsilp
    et al.
    Bovornratanaraks, Thiti
    Pinsook, Udomsilp
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Superhard Semiconducting Phase of Osmium Tetraboride Stabilizing at 11 GPa2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 40, p. 23165-23171Article in journal (Refereed)
    Abstract [en]

    Employing a systematic first-principles investigation with crystal structure searching based on an evolutionary algorithm, we have uncovered the, novel phase (P4(2)/nmc) of OsB4 with, a novel superhardness and semiconducting state. In this investigation, metal-to-semiconductor phase transition:is predicted at only a few gigapascals above ambient pressure, i.e, 11 GPa. As a result, the P4(2)/nmc phase, should potentially become a metastable phase at ambient pressure. The Vickers (polycrystalline) hardness and the band gap of the semiconducting phase are calculated to be 60 GPa and 2.90 eV, respectively. These findings indicate that the P4(2)/nmc phase might be a promising superhard-semiconducting material which could be used in cutting and drilling tools, material coating, and other advanced optical technologies. Moreover, under further compression up-to 300 Q-Pa, the semiconducting phase transforms into a metallic P6(3)/mmc phase at 134 GPa, and then another predicted metallic phase with a Circa symmetry emerges beyond 270 GPa. Both dynamic and elastic stabilities are fully investigated to ensure the existence of the predicted phases.

  • 27. Kotmool, Komsilp
    et al.
    Chakraborty, Sudip
    Bovornratanaraks, Thiti
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Role of relativity in high-pressure phase transitions of thallium2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 42983Article in journal (Refereed)
    Abstract [en]

    We demonstrate the relativistic effects in high-pressure phase transitions of heavy element thallium. The known first phase transition from h. c. p. to f. c. c. is initially investigated by various relativistic levels and exchange-correlation functionals as implemented in FPLO method, as well as scalar relativistic scheme within PAW formalism. The electronic structure calculations are interpreted from the perspective of energetic stability and electronic density of states. The full relativistic scheme (FR) within L(S) DA performs to be the scheme that resembles mostly with experimental results with a transition pressure of 3 GPa. The s-p hybridization and the valence-core overlapping of 6s and 5d states are the primary reasons behind the f. c. c. phase occurrence. A recent proposed phase, i. e., a body-centered tetragonal (b. c. t.) phase, is confirmed with a small distortion from the f. c. c. phase. We have also predicted a reversible b. c. t. -> f. c. c. phase transition at 800 GPa. This finding has been suggested that almost all the III-A elements (Ga, In and Tl) exhibit the b. c. t. -> f. c. c. phase transition at extremely high pressure.

  • 28. Lee, J. -Y
    et al.
    Punkkinen, M. P. J.
    Schönecker, Stephan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Nabi, Z.
    Kádas, K.
    Zólyomi, V.
    Koo, Y. M.
    Hu, Q. -M
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Box 516, Uppsala, Sweden.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Box 516, Uppsala, Sweden.
    Kollár, J.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Kwon, S. K.
    The surface energy and stress of metals2018In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 674, p. 51-68Article in journal (Refereed)
    Abstract [en]

    We investigated surface properties of metals by performing first-principles calculations. A systematic database was established for the surface relaxation, surface energy (γ), and surface stress (τ) for metallic elements in the periodic table. The surfaces were modeled by multi-layered slab structures along the direction of low-index surfaces. The surface energy γ of simple metals decreases as the atomic number increases in a given group, while the surface stress τ has its minimum in the middle. The transition metal series show parabolic trends for both γ and τ with a dip in the middle. The dip occurs at half-band filling due to a long-range Friedel oscillation of the surface charge density, which induces a strong stability to the Peierls-like transition. In addition, due to magnetic effects, the dips in the 3d metal series are shallower and deeper for γ and τ, respectively, than those of the 4d and 5d metals. The surface stress of the transition metals is typically positive, only Cr and Mn have a negative τ for the (100) surface facet, indicating that they are under compression. The light actinides have an increasing γ trend according to the atomic number. The present work provides a useful and consistent database for the theoretical modelling of surface phenomena.

  • 29. Manotum, R.
    et al.
    Klinkla, R.
    Pinsook, U.
    Kotmool, K.
    Tsuppayakorn-aek, P.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Condensed Matter Theory Group, Department of Physics, University of Uppsala, Box 530, SE 75121, Uppsala, Sweden.
    Bovornratanaraks, T.
    Effect of pressure on the structure stability, electronic structure and band gap engineering in Zn16O1S152018In: Computational Condensed Matter, ISSN 2352-2143, Vol. 17, article id e00332Article in journal (Refereed)
    Abstract [en]

    Crystal structures and high pressure structural phase transitions of Zn16O1S15 have been investigated using density functional theory calculation. The two candidate high pressure structures namely Wurtzite and Zincblende were examined for theirs stability and properties up to 20 GPa. The co-exist phase of both structure which occurred during the different film growth conditions was fully explained. Phonon dispersion and the Born criteria reveal that Zincblende is only stable up to 10 GPa. Besides, Wurtzite structure yield no imaginary phonon frequencies and also satisfy the elastic constants sufficiency condition up to 20 GPa which indicated that the co-exist phase would eventually become the single Wurtzite structure above 10 GPa. The electronic structure and PDOS were also fully investigated using HSE06. The multiple band gap energy and mid O-3 state between fundamental ZnS band gap was revealed for the first time. The pressure effect on their electronic structure has been investigated for possible applications in adjustable optoelectronic device. 

  • 30. Mir, Showkat H.
    et al.
    Chakraborty, Sudip
    Warna, John
    Narayan, Som
    Jha, Prakash C.
    Jha, Prafulla K.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    A comparative study of hydrogen evolution reaction on pseudo-monolayer WS2 and PtS2: insights based on the density functional theory2017In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 7, no 3, p. 687-692Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated the catalytic activity of ultrathin PtS2 and WS2 nanostructures for the hydrogen evolution reaction by electronic structure calculations based on the spin-polarised density functional theory. We also explored the effect of van der Waals interactions on the surface-adsorbate interactions. Using the adsorption free energy of H-2 as an activity descriptor, we tuned the photocatalytic water splitting activity of PtS2 and WS2 by functionalizing the individual systems with different transition metals such as Ru, Rh, Pd, Ag, Ir, Au, and Hg. The density of states was calculated along with the band structure to find the effect of different dopants on the fundamental band gap, which is one of the primary parameters in the photocatalytic water splitting.

  • 31. Naqvi, S. R.
    et al.
    Hussain, T.
    Luo, W.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Exploring Doping Characteristics of Various Adatoms on Single-Layer Stanene2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 14, p. 7667-7676Article in journal (Refereed)
    Abstract [en]

    We have performed first-principles calculations based on density functional theory to investigate the doping characteristics of 31 different adatoms on stanene monolayer, which includes the elements of alkali metals (AM), alkaline earth metals (AEM), transition metals (TMs), and groups III-VII. The most stable configurations of all the dopants have been explored by calculating and comparing binding energies of all the possible binding sites. To comment on the uniform distribution of adatoms on stanene, the adsorption energies (E-ads) of adatoms have been compared with their experimental cohesive energies (E-c,) in the bulk phase.A further comparison reveals that the binding energies of most of the studied adatoms on stanene are much stronger than other group IV monolayers. Apart from structural and binding characteristics, bond lengths, adatom adatom distance, charge-transfer mechanism, electronic properties, and work function have also been explored in pristine and doped monolayers. The strong adsorption of adatoms on stanene, tunable electronic properties, and formation of dumbbell structures in the case of AEM and TM shows that doped stanene sheets are worth further exploration.

  • 32.
    Naqvi, Syeda R.
    et al.
    Uppsala Univ, Condensed Matter Theory Grp, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Hussain, Tanveer
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia..
    Luo, Wei
    Uppsala Univ, Condensed Matter Theory Grp, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Condensed Matter Theory Grp, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden.
    Metallized siligraphene nanosheets (SiC7) as high capacity hydrogen storage materials2018In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 7, p. 3802-3813Article in journal (Refereed)
    Abstract [en]

    A planar honeycomb monolayer of siligraphene (SiC7) could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van der Waals-induced first principles calculations based on density functional theory (DFT), we have explored the structural, electronic, and hydrogen (H-2) storage characteristics of SiC7 sheets decorated with various light metals. The binding energies of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca),scandium (Sc), and titanium (Ti) dopants on a SiC7 monolayer were studied at various doping concentrations, and found to be strong enough to counteract the metal clustering effect. We further verified the stabilities of the metallized SiC7 sheets at room temperature using ab initio molecular dynamics (MD) simulations. Bader charge analysis revealed that upon adsorption, due to the difference in electronegativity, all the metal adatoms donated a fraction of their electronic charges to the SiC7 sheet. Each partially charged metal center on the SiC(7)sheets could bind a maximum of 4 to 5 H-2 molecules. A high H-2 gravimetric density was achieved for several dopants at a doping concentration of 12.50%. The H-2 binding energies were found to fall within the ideal range of 0.2-0.6 eV. Based on these findings, we propose that metal-doped SiC7 sheets can operate as efficient H-2 storage media under ambient conditions.

  • 33.
    Naqvi, Syeda Rabab
    et al.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Rao, Gollu Sankar
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland..
    Luo, Wei
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden.
    Hussain, Tanveer
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia..
    Hexagonal Boron Nitride (h-BN) Sheets Decorated with OLi, ONa, and Li2F Molecules for Enhanced Energy Storage2017In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 18, no 5, p. 513-518Article in journal (Refereed)
    Abstract [en]

    First-principles electronic structure calculations were carried out on hexagonal boron nitride (h-BN) sheets functionalized with small molecules, such as OLi, ONa, and Li2F, to study their hydrogen (H-2) storage properties. We found that OLi and ONa strongly adsorb on h-BN sheets with reasonably large inter-adsorbent separations, which is desirable for H-2 storage. Ab initio molecular dynamics (MD) simulations further confirmed the structural stability of OLi-BN and ONa-BN systems at 400K. On the other hand, Li2F molecules form clusters over the surface of h-BN at higher temperatures. We performed a Bader charge investigation to explore the nature of binding between the functionalized molecules and h-BN sheets. The density of states (DOS) revealed that functionalized h-BN sheets become metallic with two-sided coverage of each type of molecules. Hydrogenation of OLi-BN and ONa-BN revealed that the functionalized systems adsorb multiple H-2 molecules around the Li and Na atoms, with H-2 adsorption energies ranging from 0.20 to 0.28eV, which is desirable for an efficient H-2 storage material.

  • 34.
    Negi, Devendra Singh
    et al.
    Max Planck Inst Solid State Res, Stuttgart Ctr Electron Microscopy, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Singh, Deobrat
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-77120 Uppsala, Sweden..
    van Aken, Peter A.
    Max Planck Inst Solid State Res, Stuttgart Ctr Electron Microscopy, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Spin-entropy induced thermopower and spin-blockade effect in CoO2019In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 100, no 14, article id 144108Article in journal (Refereed)
    Abstract [en]

    We report spin-entropy-induced thermopower and the occurrence of a spin-blockade effect in stoichiometric disordered CoO. Cation defect-driven distortion in the octahedral ligand field of CoO leads to a charge transfer process and favors the stabilization of Co+3 charge states at defect adjacent atomic sites. Moreover, a higher extent of local stoichiometric disruption triggers the spin crossover and magnetic collapse into a Co+3 state. Degenerated spin-orbital states on vacancy neighbored atomic sites render the spin-orbital degeneracy to enhance the thermopower in CoO. Furthermore, we unravel an operating spin-blockade effect in CoO. The localized combination of active magnetic states-high-spin Co+2 and neutral magnetic states-low-spin Co+3 on alternate atomic sites suppress the charge carrier hopping due to a spin blockade. In the pursuit of efficient thermoelectric material, the present investigation explores the potential of the recipe of spin entropy and defect-engineered CoO.

  • 35.
    Pakeetood, Patompob
    et al.
    Kasetsart Univ, Fac Sci, Dept Phys, Bangkok 10900, Thailand..
    Reunchan, Pakpoom
    Kasetsart Univ, Fac Sci, Dept Phys, Bangkok 10900, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Boonchun, Adisak
    Kasetsart Univ, Fac Sci, Dept Phys, Bangkok 10900, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Limpijumnong, Sukit
    Inst Promot Teaching Sci & Technol, 924 Sukhumvit Rd, Bangkok 10110, Thailand..
    Munprom, Ratiporn
    Kasetsart Univ, Fac Engn, Dept Mat Engn, Bangkok 10900, Thailand..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Mat Theory Div, Box 530, SE-75121 Uppsala, Sweden..
    T-Thienprasert, Jiraroj
    Kasetsart Univ, Fac Sci, Dept Phys, Bangkok 10900, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Hybrid-Functional Study of Native Defects and W/Mo-Doped in Monoclinic-Bismuth Vanadate2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 23, p. 14508-14516Article in journal (Refereed)
    Abstract [en]

    Monoclinic scheelite (ms) BiVO4 is recognized as one of the most promising photocatalyst materials due to its band gap as well as band-edge positions. Several theoretical and experimental works have been dedicated to improving the photocatalytic activity of ms-BiVO4. It has been reported that doping ms-BiVO4 with either W or Mo can enhance its photocatalytic activity compared to the undoped one. Further, codoping with W and Mo can improve the photocatalytic activity. Here, we systematically investigate all native and W/Mo-related defects in ms-BiVO4 by using density functional theory with hybrid functional. For undoped ms-BiVO4, we reveal that vacancies are the most dominant intrinsic defects and these defects compensate themselves leading to moderate n-type conductivity in O-poor growth condition. For W/Mo-doped ms-BiVO4, W and Mo are likely to substitute for V atom under all crystal growth conditions. While W v defect is a shallow donor, Mo v defect creates a defect level below the conduction band edge. This implies that doping with W can gain more photocatalytic efficiency, which agrees well with experiment. Interestingly, we find that two donors, i.e., W v and Mo v defects, prefer to form a complex defect becoming a shallow double donor. This can improve the electrical conductivity of W/Mo-codoped ms-BiVO4, which helps enhance its photocatalytic performance. In addition, the formation of donor-donor complexes is quite stable and helps improve material property.

  • 36.
    Panigrahi, P.
    et al.
    Hindustan Inst Technol & Sci, Clean Energy & Nano Convergence Ctr, Madras 603103, Tamil Nadu, India..
    Dhinakaran, A. K.
    Hindustan Inst Technol & Sci, Clean Energy & Nano Convergence Ctr, Madras 603103, Tamil Nadu, India..
    Naqvi, S. R.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Gollu, S. R.
    Nanyang Technol Univ, Sch Elect & Elect Engn, 50 Nanyang Ave, Singapore 639798, Singapore..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Hussain, T.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia.;Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Light metal decorated graphdiyne nanosheets for reversible hydrogen storage2018In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 29, no 35, article id 355401Article in journal (Refereed)
    Abstract [en]

    The sensitive nature of molecular hydrogen (H-2) interaction with the surfaces of pristine and functionalized nanostructures, especially two-dimensional materials, has been a subject of debate for a while now. An accurate approximation of the H-2 adsorption mechanism has vital significance for fields such as H2 storage applications. Owing to the importance of this issue, we have performed a comprehensive density functional theory (DFT) study by means of several different approximations to investigate the structural, electronic, charge transfer and energy storage properties of pristine and functionalized graphdiyne (GDY) nanosheets. The dopants considered here include the light metals Li, Na, K, Ca, Sc and Ti, which have a uniform distribution over GDY even at high doping concentration due to their strong binding and charge transfer mechanism. Upon 11% of metal functionalization, GDY changes into a metallic state from being a small band-gap semiconductor. Such situations turn the dopants to a partial positive state, which is favorable for adsorption of H-2 molecules. The adsorption mechanism of H-2 on GDY has been studied and compared by different methods like generalized gradient approximation, van der Waals density functional and DFT-D3 functionals. It has been established that each functionalized system anchors multiple H-2 molecules with adsorption energies that fall into a suitable range regardless of the functional used for approximations. A significantly high H-2 storage capacity would guarantee that light metal-doped GDY nanosheets could serve as efficient and reversible H-2 storage materials.

  • 37. Panigrahi, P.
    et al.
    Dhinakaran, A. K.
    Sekar, Y.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Hussain, T.
    Efficient Adsorption Characteristics of Pristine and Silver-Doped Graphene Oxide Towards Contaminants: A Potential Membrane Material for Water Purification?2018In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 17, p. 2250-2257Article in journal (Refereed)
    Abstract [en]

    In this work, we have investigated the potential of pristine and silver (Ag)-functionalized graphene oxide monolayers GO (GO−Ag) as efficient membranes for water filtration. Our first principles calculations based on density functional theory (DFT) reveal the hydrophilic nature of GO surfaces. The phonon frequency calculations within density functional perturbation theory (DFPT) confirmed the stability of GO sheets in aqueous media. Van der Waals-corrected binding energies of GO sheet towards heavy metals suggest that even pristine GO sheets are completely impermeable to various heavy metals like arsenic (As) and lead (Pb). However, compared to GO, the GO−Ag sheets have a much higher affinity towards the three amino acids histidine, phenyl-alanine and tyrosine, which are the main component of a bacteria cell wall. The GO−Ag sheet is found to be extremely efficient for bacteria inactivation. 

  • 38.
    Prasongkit, Jariyanee
    et al.
    Nakhon Phanom Univ, Fac Sci, Div Phys, Nakhon Phanom 48000, Thailand.;Commiss Higher Educ, Thailand Ctr Excellence Phys, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand..
    Shukla, Vivekanand
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Grigoriev, Anton
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Amornkitbamrung, Vittaya
    Khon Kaen Univ, Fac Sci, Dept Phys, 123 Mittraphab Rd, Khon Kaen 40002, Thailand.;Khon Kaen Univ, Fac Sci, Inst Nanomat Res & Innovat Energy, Dept Phys, 123 Mittraphab Rd, Khon Kaen 40002, Thailand..
    Ultrahigh-sensitive gas sensors based on doped phosphorene: A first-principles investigation2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 497, article id UNSP 143660Article in journal (Refereed)
    Abstract [en]

    Recent significant advancements have been made in demonstrating the usage of phosphorene to detect the presence of gases leading to a new breed of gas sensor device. Based on pristine phosphorene, the devices can detect a small concentration of adsorbed molecules with high sensitivity at room temperature. In this work, we propose doping silicon and sulfur impurity atoms into phosphorene to drastically improve its gas sensing performance. We use a combination of density functional theory and non-equilibrium Green's function method to evaluate the sensitivity and selectivity of doped phosphorene nanosensors for four gases (NO, NO2, NH3, and CO). Both devices demonstrate a prominent distinction in conductance when the gas molecules are exposed to the sensor surface. We suggest the doped phosphorene may present advantages over the device based purely on phosphorene due to the ability to discriminate different gases controlled by types of dopants.

  • 39. Qian, Z.
    et al.
    Raghubanshi, H.
    Sterlin Leo Hudson, M.
    Srivastava, O. N.
    Liu, X.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Ab initio insight into graphene nanofibers to destabilize hydrazine borane for hydrogen release2017In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 669, p. 404-411Article in journal (Refereed)
    Abstract [en]

    We report the potential destabilizing effects of graphene nanofibers on the hydrogen release property of hydrazine borane via state-of-the-art ab initio calculations for the first time. Interactions of a hydrazine borane cluster with two types of graphene patch edges which exist abundantly in our synthesized graphene nanofibers have been investigated. It is found that both zigzag and armchair edges can greatly weaken the H-host bonds (especially the middle N[sbnd]H bond) of hydrazine borane. The dramatic decrease in hydrogen removal energy is caused by the strong interaction between hydrazine borane and the graphene patch edges concerning the electronic charge density redistribution.

  • 40. Qian, Zhao
    et al.
    Guo, Weimin
    Jiang, Guanzhong
    Xu, Shaokun
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Sweden.
    Liu, Xiangfa
    Revisiting Mg-Mg2Ni System from Electronic Perspective2017In: METALS, ISSN 2075-4701, Vol. 7, no 11, article id 489Article in journal (Refereed)
    Abstract [en]

    Both Mg and Mg2Ni are promising electrode materials in conversion-type secondary batteries. Earlier studies have shown their single-phase prospects in electro-devices, while in this work, we have quantitatively reported the electronic properties of their dual-phase materials, that is, Mg-Mg2Ni alloys, and analyzed the underlying reasons behind the property changes of materials. The hypoeutectic Mg-Mg2Ni alloys are found to be evidently more conductive than the hypereutectic Mg-Mg2Ni system. The density functional theory (DFT) calculations give the intrinsic origin of electronic structures of both Mg2Ni and Mg. The morphology of quasi-nanoscale eutectics is another factor that can affect the electronic properties of the investigated alloy system; that is, the electrical property change of the investigated alloys system is due to a combination of the intrinsic property difference between the two constituting phases and the change of eutectic microstructures that affect electron scattering. In addition, regarding the Mg-Mg2Ni alloy design for device applications, the electronic property and mechanical aspect should be well balanced.

  • 41. Ragupathi, V.
    et al.
    Safiq, M.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Sweden.
    Panigrahi, P.
    Hussain, Tanveer
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Sweden.
    Raman, S.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Sweden.
    Nagarajan, G. S.
    Enhanced electrochemical performance of LiMnBO3 with conductive glassy phase: a prospective cathode material for lithium-ion battery2017In: Ionics (Kiel), ISSN 0947-7047, E-ISSN 1862-0760, Vol. 23, no 7, p. 1645-1653Article in journal (Refereed)
    Abstract [en]

    LiMnBO3 has been identified as a promising cathode material for next-generation lithium-ion batteries. In this study, LiMnBO3 along with glassy lithium borate material (LiMnBO3 (II)) is synthesized by sol-gel method. X-ray diffraction (XRD) analysis depicts the existence of LiBO2 glassy phase along with m-LiMnBO3 phase. Transmission electron microscopy (TEM) analysis confirms the presence of LiBO2 glassy phase. An enhanced electrical conductivity of 3.64 x 10(-7) S/cm is observed for LiMnBO3 (II). The LiBO2 glassy phase is found to promote the Li reaction kinetics in LiMnBO3 (II). The synthesized LiMnBO3 (II) delivers a first discharge capacity of 310 mAh g(-1) within a potential window of 1.5-4.5 V at C/10 rate. Further, a discharge capacity of 186 mAh g(-1) at the 27th cycle shows a better cycle performance. The enhanced capacity is due to the presence of LiBO2 glassy phase and more than one Li-ion transfer in the lithium-rich stoichiometry of LiMnBO3 (II). Density functional theory calculation reveals the exact electronic structure of m-LiMnBO3 with a band gap of 3.05 eV. A charge transfer mechanism is predicted for delithiation process of m-LiMnBO3.

  • 42.
    Ramzan, M.
    et al.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.). Royal Inst Technol KTH, Dept Mat & Engn, SE-10044 Stockholm, Sweden..
    Erratum to: Role of correlation effects in the superconducting material2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 4, article id 049901Article in journal (Refereed)
  • 43. Saraf, D.
    et al.
    Chakraborty, S.
    Kshirsagar, A.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    In pursuit of bifunctional catalytic activity in PdS2 pseudo-monolayer through reaction coordinate mapping2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 49, p. 283-289Article in journal (Refereed)
    Abstract [en]

    We have investigated the photocatalytic efficiency and corresponding hydrogen and oxygen evolution reactions (HER and OER) through different functionalization of stable 1T palladium disulfide (PdS2) monolayer. The electronic structure calculations based on Density Functional Theory (DFT) formalism, have been performed along with the corresponding optical properties of functionalized and S-mono-vacancy defected 1T PdS2 monolayer. The optimum band gap required for water splitting makes this two-dimensional material an exciting promise for photocatalysis process. In this work, we have not only envisaged the photocatalytic activity, but also the specific reaction coordinates for HER and OER based on the adsorption energies of the intermediates of the individual reaction. Functionalization of 1T PdS2 monolayer is done by replacing the anion (S) site with P, N and C functionalized atoms and also by creating a mono-vacancy defect at the same site. We have also determined (i) the stability of the functionalized 1T PdS2 monolayer based on the phonon dispersion calculations and (ii) the respective work function of the individual systems. The steady optical response in the visible range is in favour of the photocatalytic activity of the monolayer, while the corresponding reaction coordinates predict the suitability of the functionalized and defected monolayer for HER and OER mechanism. The mono-vacancy defected and N-functionalized PdS⁠2 monolayer have emerged as the most promising systems for OER and HER activities respectively. Overall, we have predicted that the bifunctional catalytic activity can be achieved through functionalization and vacancy defect in PdS⁠2 monolayer.

  • 44. Shukla, V.
    et al.
    Araujo, R. B.
    Jena, N. K.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Borophene's tryst with stability: Exploring 2D hydrogen boride as an electrode for rechargeable batteries2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 34, p. 22008-22016Article in journal (Refereed)
    Abstract [en]

    Graphene's emergence can be viewed as a positive upheaval in 2D materials research. Along the same line, the realization of a related elemental 2D material, borophene, is another breakthrough. To circumvent the stability issues of borophene, which is reported to have been synthesized on metallic substrates under extreme conditions, hydrogenation of borophene (otherwise called as borophane or hydrogen boride or boron hydride) has been a plausible solution, but only proposed computationally. A recent report (H. Nishino, T. Fujita, N. T. Cuong, S. Tominaka, M. Miyauchi, S. Iimura, A. Hirata, N. Umezawa, S. Okada, E. Nishibori, A. Fujino, T. Fujimori, S. Ito, J. Nakamura, H. Hosono and T. Kondo, J. Am. Chem. Soc., 2017, 139(39), 13761-13769) brings to fore its experimental realization. Our current study delves into the possibilities of employing this intriguing 2D hydrogen boride as anodes in Li/Na ion batteries. Using first-principles density functional theory methods, we computed relevant properties such as the ion (Li/Na) adsorption behavior, the possible pathways of ionic diffusion with the estimation of barriers as well as the theoretical specific capacities and average voltages to uniquely demonstrate that this material is of particular significance for battery applications. It is noted that the use of hydrogen boride leads to a high specific capacity of 861.78 mA h g-1 for Li ions, which is remarkably higher than the value reported in relation to its computationally predicted structure. Furthermore, Na ion intercalation leads to negative voltage profiles, implying the unsuitability of 2D hydrogen boride for this particular ion. Our findings are timely and pertinent towards adding insightful details relevant to the progress of applications of 2D materials for energy storage.

  • 45. Shukla, V.
    et al.
    Araujo, R. B.
    Jena, N. K.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    The curious case of two dimensional Si2BN: A high-capacity battery anode material2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 41, p. 251-260Article in journal (Refereed)
    Abstract [en]

    The ubiquity of silicon in the semiconductor industry and its unique charge transport features has consistently fueled interest in this element and recent realization 2D silicene is a new feather in its cap. In what could be considered as opening up the Pandora's box with many possible virtues, buckled silicene, planar graphene and a host of other newly discovered 2D materials have redefined a whole new paradigm of research. To this end, the quest for new 2D materials and finding potential applications, particularly to the realm of energy storage, is a curiosity driven task. From first principle density functional theory studies, a newly reported graphene like 2D material Si2BN is investigated as a probable anode material for Li and Na ion batteries. In contrast to pristine silicene, which is inherently buckled, the material Si2BN is planar. However, an interesting transition from planar to buckled structure takes place upon subsequent adsorption of Li and Na ions. Concomitantly, this transition is associated with superior specific capacity (1158.5 and 993.0 mA h/g respectively for Li and Na) which is significantly higher than several other 2D analogues. Furthermore, the substrate Si2BN regains the planar structure on subsequent desorption of ions and stability of the material remains intact, as evidenced from ab initio molecular dynamics simulations. As we delve deep into the electronic structure and compute the diffusion pathways and barriers, it is observed that the ionic diffusion is very fast with significantly lesser barrier heights, particularly for Na-ion. These findings suggest that for the 2D Si2BN, there is no diminution in order to be a potential anode material for Li and Na ion batteries.

  • 46. Shukla, V.
    et al.
    Jena, N. K.
    Naqvi, S. R.
    Luo, W.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Modelling high-performing batteries with Mxenes: The case of S-functionalized two-dimensional nitride Mxene electrode2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 58, p. 877-885Article in journal (Refereed)
    Abstract [en]

    Recent upsurge in the two-dimensional (2D) materials have established their larger role on energy storage applications. To this end, Mxene represent a new paradigm extending beyond the realm of oft-explored elemental 2D materials beginning with graphene. Here in, we employed first principles modelling based on density functional theory to investigate the role of S-functionalized Nitride Mxenes as anodes for Li/Na ion batteries. To be specific, V 2 NS 2 and Ti 2 NS 2 have been explored with a focus on computing meaningful descriptors to quantify these 2D materials to be optimally performing electrodes. The Li/Na ion adsorption energies are found to be high (>-2 eV) on both the surfaces and associated with significant charge transfer. Interestingly, this ion intercalation can reach up to multilayers which essentially affords higher specific capacity for the substrate. Particularly, these two 2D materials (V 2 NS 2 and Ti 2 NS 2 ) have been found to be more suitable for Li-ion batteries with estimated theoretical capacities of 299.52 mAh g −1 and 308.28 mAh g −1 respectively. We have also probed the diffusion barriers of ion migration on these two surfaces and these are found to be ultrafast in nature. All these unique features qualify these Mxenes to be potential anode materials for rechargeable batteries and likely to draw imminent attention.

  • 47.
    Shukla, Vivekanand
    et al.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Grigoriev, Anton
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Jena, Naresh K.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 516, SE-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Strain controlled electronic and transport anisotropies in two-dimensional borophene sheets2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 35, p. 22952-22960Article in journal (Refereed)
    Abstract [en]

    Two recent reports on realization of an elemental 2D analogue of graphene:borophene (Science, 2015, 350, 1513-1516; Nat. Chem., 2016, 8, 563-568) focus on the inherent anisotropy and directional dependence of the electronic properties of borophene polymorphs. Achieving stable 2D borophene structures may lead to some degree of strain in the system because of the substrate-lattice mismatch. We use first principles density functional theory (DFT) calculations to study the structural, electronic and transport properties of (12) and -borophene polymorphs. We verified the directional dependency and found the tunable anisotropic behavior of the transport properties in these two polymorphs. We find that strain as low as 6% brings remarkable changes in the properties of these two structures. We further investigate current-voltage (I-V) characteristics in the low bias regime after applying a strain to see how the anisotropy of the current is affected. Such observations like the sizeable tuning of transport and I-V characteristics at the expense of minimal strain suggest the suitability of 2D borophene for futuristic device applications.

  • 48. Shukla, Vivekanand
    et al.
    Jena, Naresh K.
    Grigoriev, Anton
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Prospects of Graphene-hBN Heterostructure Nanogap for DNA Sequencing2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 46, p. 39945-39952Article in journal (Refereed)
    Abstract [en]

    Recent advances in solid-state nano-device-based DNA sequencing are at the helm of the development of a new paradigm, commonly referred to as personalized medicines. Paying heed to a timely need for standardizing robust nanodevices for cheap, fast, and scalable DNA detection, in this article, the nanogap formed by the lateral heterostructure of graphene and hexagonal boron nitride (hBN) is explored as a potential architecture. These heterostructures have been realized experimentally, and our study boasts the idea that the passivation of the edge of the graphene electrode with hBN will solve many of practical problems, such as high reactivity of the graphene edge and difficulty in controlled engineering of the graphene edge structure, while retaining the nanogap setup as a useful nanodevice for sensing applications. Employing first-principle density-functional-theory-based nonequilibrium Greens function methods, we identify that the DNA building blocks, nucleobases, uniquely couple with the states of the nanogap, and the resulting induced states can be attributed as leaving a fingerprint of the DNA sequence in the computed current-voltage (I-V) characteristic. Two bias windows are put forward: lower (1-1.2 V) and higher (2.7-3 V), where unique identification of all four bases is possible from the current traces, although higher sensitivity is obtained at the higher voltage window. Our study can be a practical guide for experimentalists toward development of a nanodevice DNA sensor based on graphene-hBN heterostructures.

  • 49. Shukla, Vivekanand
    et al.
    Warna, John
    Jena, Naresh K.
    Grigoriev, Anton
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Toward the Realization of 2D Borophene Based Gas Sensor2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 48, p. 26869-26876Article in journal (Refereed)
    Abstract [en]

    To the league of rapidly expanding 2D materials, borophene is a recent addition. Herein, a combination of ab initio density functional theory (DFT) and nonequilibrium Green's function (NEGF) based methods is used to estimate the prospects of this promising elemental 2D material for gas sensing applications. We note that the binding of target gas molecules such as CO, NO, NO2, NH3, and CO2 is quite strong on the borophene surface. Interestingly, our computed binding energies are far stronger than several other reported 2D materials like graphene, MoS2, and phosphorene. Further rationalization of stronger binding is made with the help of charge transfer analysis. The sensitivity of the borophene for these gases is also interpreted in terms of computing the vibrational spectra of the adsorbed gases on top of borophene, which show dramatic shift from their gas phase reference values. The metallic nature of borophene enables us to devise a setup considering the same substrate as electrodes. From the computation of the transmission function of system (gas + borophene), appreciable changes in the transmission functions are noted compared to pristine borophene surface. The measurements of current-voltage (I-V) characteristics unambiguously demonstrate the presence and absence of gas molecules (acting as ON and OFF states), strengthening the plausibility of a borophene based gas sensing device. As we extol the extraordinary sensitivity of borophene, we assert that this elemental 2D material is likely to attract subsequent interest.

  • 50.
    Singh, Deobrat
    et al.
    Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden..
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, Box 516, S-75120 Uppsala, Sweden.;Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Enhanced Optoelectronic and Thermoelectric Properties by Intrinsic Structural Defects in Monolayer HfS22019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 9, p. 6891-6903Article in journal (Refereed)
    Abstract [en]

    In the present work, we have studied the electronic, optical, and thermoelectric properties of a monolayer of pristine HfS2 and two types of vacancy and two types of dopant by using first-principles calculations. These configurations with single atom vacancy (Hf and S atoms) and single atom dopant in place of a sulfur atom are energetically more favorable. The electronic properties of HfS2 monolayer are significantly affected by vacancies as well as dopants. Also, it transforms indirect-band-gap semiconducting behavior to direct-band-gap semiconducting behavior and semiconductor-to-metal HfS2 occurs during the structural defect. The variation in the work function of HfS2 monolayer by vacancy, as well as dopant, indicates the change in conductivity. The structural defect enhancing the light absorption as well as the conductivity of HfS2 monolayer and H-phase of it is suitable for UV light absorption while the T-phase is suitable for visible light absorption. From the thermoelectric properties, the relatively high Seebeck coefficient and it is found to be 2867 and 2902 mu V K-1 for doped P atom in the T-phase and the pristine H-phase, respectively, at room temperature. The figure of merit (ZT) at 300 K is determined to be 1 for the T-phase and 1.05 for the H-phase, while, at a higher temperature, ZT = 1.23 for the Hf vacancy in the T-phase. Such analysis reveals that the structural defects not only significantly affect the electronic properties, but they also can be used as an efficient way to modulate the thermoelectric properties and enhance ZT. The theoretical results suggest that the two-dimensional HfS2 monolayer is very useful in high-performance optoelectronic and thermoelectric devices.

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