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Träfflista för sökning "LAR1:uu ;pers:(Ahuja Rajeev);pers:(Pathak Biswarup)"

Sökning: LAR1:uu > Ahuja Rajeev > Pathak Biswarup

  • Resultat 1-10 av 29
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1.
  • Banerjee, Paramita, et al. (författare)
  • First principles design of Li functionalized hydrogenated h-BN nanosheet for hydrogen storage
  • 2016
  • Ingår i: International journal of hydrogen energy. - 0360-3199. ; 41:32, s. 14437-14446
  • Tidskriftsartikel (refereegranskat)abstract
    • Employing first principles density functional theory (DFT) based approach, the structure, stability and hydrogen storage efficiency of a hydrogenated hexagonal boron nitride sheet (BHNH chair conformer) functionalized by the lightest alkali metal atom Li has been explored here in details. Substituting one hydrogen atom from both B and N sides of BHNH sheet by a Li atom, we have found that Li becomes cationic and acts as a binding site to adsorb hydrogen molecules. The stability of this Li-substituted BHNH sheet has been indicated via Ab-initio Molecular Dynamics (AIMD) simulation upto 400 K. The binding energy (similar to 0.18-0.3 eV/H-2 molecule) and gravimetric density (similar to 6 wt %) (upto similar to 200 K) of the hydrogen molecules fall in the required window for practical hydrogen storage. AIMD simulation indicates complete dehydrogenation from this system occurs at similar to 400 K, thereby predicting the suitability of this system from the point of view of efficient hydrogen storage.
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2.
  • Choudhuri, Indrani, et al. (författare)
  • B-N@Graphene : Highly Sensitive and Selective Gas Sensor
  • 2015
  • Ingår i: The Journal of Physical Chemistry C. - 1932-7447. ; 119:44, s. 24827-24836
  • Tidskriftsartikel (refereegranskat)abstract
    • We have performed density functional theory (DFT) calculations to study the gas (CO, CO2, NO, and NO2) sensing mechanism of pure and doped (B@, N@, and B-N@) graphene surfaces. The calculated adsorption energies of the various toxic gases (CO, CO2, NO, and NO2) on the pure and doped graphene surfaces show, doping improves adsorption energy and selectivity. The electronic properties of the B-N@graphene surfaces change significantly compared to pure and B@ and N@graphene surfaces, while selective gas molecules are adsorbed. So, we report B-N codoping on graphene can be highly sensitive and selective for semiconductor-based gas sensor.
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3.
  • Guo, Zhonglu, et al. (författare)
  • Band gap engineering in huge-gap semiconductor SrZrO3 for visible-light photocatalysis
  • 2014
  • Ingår i: International journal of hydrogen energy. - 0360-3199. ; 39:5, s. 2042-2048
  • Tidskriftsartikel (refereegranskat)abstract
    • Using SrZrO3 (SZO, the intrinsic band gap being 5.6 eV) as an example, we have investigated the design principles for huge-gap semiconductors with band gap larger than 5 eV for the application of efficient visible-light driven photocatalysts for splitting water into hydrogen. Based on the hybrid density function calculations, the electronic structures of mono-doped and co-doped SZO are investigated to obtain design principles for improving their photocatalytic activity in hydrogen generation. The cationic-anionic co-doping in SZO could reduce the band gap significantly and its electronic band position is excellent for the visible-light photocatalysis. This work reports a new type of candidate material for visible-light driven photocatalysis, i.e., huge-gap semiconductors with band gap larger than 5 eV. Furthermore, based on the present results we have proposed the design principles for band gap engineering that provides general guideline for other huge-gap semiconductors.
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4.
  • Hussain, Tanveer, et al. (författare)
  • Ab initio study of lithium-doped graphane for hydrogen storage
  • 2011
  • Ingår i: Europhysics letters. - 0295-5075. ; 96:2, s. 27013
  • Tidskriftsartikel (refereegranskat)abstract
    • Based on the first-principle density functional calculations we predict that Li-doped graphane (prehydrogenated graphene) can be a potential candidate for hydrogen storage. The calculated Li-binding energy on graphane is significantly higher than the Li bulk's cohesive energy ruling out any possibility of cluster formations in the Li-doped graphane. Our study shows that even with very low concentration (5.56%) of Li doping, the Li-graphane sheet can achieve a reasonable hydrogen storage capacity of 3.23 wt.%. The van der Waals corrected H(2) binding energies fall within the range of 0.12-0.29 eV, suitable for practical H(2) storage applications. 
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5.
  • Hussain, Tanveer, et al. (författare)
  • Calcium doped graphane as a hydrogen storage material
  • 2012
  • Ingår i: Applied Physics Letters. - 0003-6951. ; 100:18, s. 183902
  • Tidskriftsartikel (refereegranskat)abstract
    • On the basis of first principle density functional theory, we have studied the stability, electronic structure, and hydrogen storage capacity of a monolayer calcium doped graphane (CHCa). The stability of CHCa was further investigated using the ab initio molecular dynamics study. The binding energy of Ca on graphane sheet was found to be higher than its bulk cohesive energy, which indicates the stability of CHCa. It was observed that with a doping concentration of 11.11% of Ca on graphane sheet, a reasonably good H-2 storage capacity of 6 wt. % could be attained. The adsorption energies of H-2 were found to be 0.1 eV, within the range of practical H-2 storage applications.
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6.
  • Hussain, Tanveer, et al. (författare)
  • Improvement in the hydrogen desorption from MgH2 upon transition metals doping A hybrid density functional calculations
  • 2013
  • Ingår i: AIP Advances. - 2158-3226. ; 3:10, s. 102117
  • Tidskriftsartikel (refereegranskat)abstract
    • This study deals with the investigations of structural, electronic and thermodynamic properties of MgH2 doped with selected transition metals (TMs) by means of hybrid density functional theory (PBE0). On the structural side, the calculated lattice parameters and equilibrium volumes increase in case of Sc, Zr and Y opposite to all the other dopants indicating volumetrically increased hydrogen density. Except Fe, all the dopants improve the kinetics of MgH2 by reducing the heat of adsorption with Cu, Nb, Ni and V proving more efficient than others studied TM's. The electronic properties have been studied by density of states and correlated with hydrogen adsorption energies.
7.
  • Hussain, Tanveer, et al. (författare)
  • Transition Metals Doped MgH2 for Hydrogen Storage: A Hybrid Density Functional Calculations
  • 2013
  • Ingår i: AIP Advances. - Uppsala.
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we have investigated the structural, electronic and thermodynamicproperties of MgH2 doped with selected transition metals (TMs) by means of hybriddensity functional theory (PBE0). On the structural side, the calculated latticeparameters and equilibrium volumes increase in case of Sc, Zr and Y opposite to allthe other dopants indicating volumetrically increased hydrogen density. Except Fe, allthe dopants improve the kinetics of MgH2 by reducing the heat of adsorption with Cu,Nb, Ni and V proving more efficient than others studied TM’s. The electronicproperties have been studied by density of states and correlated with hydrogenadsorption energies.
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8.
  • Jiang, Xue, et al. (författare)
  • Graphene oxide as a chemically tunable 2-D material for visible-light photocatalyst applications
  • 2013
  • Ingår i: Journal of Catalysis. - 0021-9517. ; 299, s. 204-209
  • Tidskriftsartikel (refereegranskat)abstract
    • To elucidate the usage of graphene oxide (GO) as a photocatalysis material, we have studied the effect of epoxy and hydroxyl functionalization on the electronic structure, work function, CBM/VBM position, and optical absorption spectra of GO using density functional theory calculations. By varying the coverage and relative ratio of the surface epoxy (-O-) and hydroxyl (-OH) groups, both band gap and work function of the GO materials can be tuned to meet the requirement of photocatalyst. Interestingly, the electronic structures of GO materials with 40-50% (33-67%) coverage and OH:O ratio of 2:1(1:1) are suitable for both reduction and oxidation reactions for water splitting. Among of these systems, the GO composition with 50% coverage and OH:O (1:1) ratio can be very promising materials for visible-light-driven photocatalyst. Our results not only explain the recent experimental observations about 2-D graphene oxide as promising visible-light-driven photocatalyst materials but can also be very helpful in designing the optimal composition for higher performance.
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9.
  • Kaewmaraya, Thanayut, et al. (författare)
  • Water adsorption on ZnO(10(1)over-bar0) : The role of intrinsic defects
  • 2012
  • Ingår i: Europhysics letters. - 0295-5075. ; 97:1, s. 17014
  • Tidskriftsartikel (refereegranskat)abstract
    • Density functional theory (DFT) calculations have been performed to investigate the interaction of water molecules with bare and defective ZnO(10 (1) over bar0) surfaces. We show that at high coverages water molecules avoid adsorption close to defect sites, whereas at low coverages adsorption on defective surfaces show a similar adsorption pattern to those adsorbed on the defect-free surface, adsorbing in a molecular fashion. Finally we show that the electronic structure of the defective non-polar surface is not much affected by the adsorption of water, with exception of the O-defect surfaces.
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10.
  • Li, Yunguo, et al. (författare)
  • Metal-decorated graphene oxide for ammonia adsorption
  • 2013
  • Ingår i: Europhysics letters. - 0295-5075. ; 103:2, s. 28007
  • Tidskriftsartikel (refereegranskat)abstract
    • Based on the first-principles density functional theory, we have studied the stability, electronic structure and ammonia storage capacity of metal-decorated graphene oxide (GO). Metal atoms (Mg and Li) are bonded strongly to the epoxy oxygen atoms on the surface of the GO sheet, which can act as high-surface-area adsorbent for the ammonia uptake and release. Each metal atom can bind several ammonia molecules around itself with a reasonable binding energy. We find metal-decorated GO can store up to tens of moles of ammonia per kilogram, which is far better than the recently reported excellent ammonia adsorption by GO.
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