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

Sökning: LAR1:uu > Ahuja Rajeev > Pathak Biswarup

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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.
  • 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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4.
  • 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.
5.
  • 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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6.
  • 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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7.
  • 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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8.
  • Li, Yunguo, et al. (författare)
  • Strain-induced stabilization of Al functionalization in graphene oxide nanosheet for enhanced NH3 storage
  • 2013
  • Ingår i: Applied Physics Letters. - American Institute of Physics (AIP). - 0003-6951. ; 102:24, s. 243905
  • Tidskriftsartikel (refereegranskat)abstract
    • Strain effects on the stabilization of Al ad-atom on graphene oxide (GO) nanosheet as well as its implications for NH3 storage have been investigated using first-principles calculations. Tensile strain is found to be very effective in stabilizing the Al ad-atom on GO. It strengthens the C-O bonds through an enhanced charge transfer from C to O atoms. Interestingly, Al's stability is governed by the bond strength of C-O rather than that of Al-O. Optimally strained Al-functionalized GO binds up to 6 NH3 molecules, while it binds no NH3 molecule in unstrained condition.
9.
  • Liu, Peng, et al. (författare)
  • Anion-Anion Mediated Coupling in Layered Perovskite La2Ti2O7 for Visible Light Photocatalysis
  • 2013
  • Ingår i: The Journal of Physical Chemistry C. - 1932-7447. ; 117:27, s. 13845-13852
  • Tidskriftsartikel (refereegranskat)abstract
    • Anionic-anionic (N-N, P-P, N-P, and C-S) mediated coupling can be introduced in the layered perovskite La2Ti2O7 structure for visible light photocatalysis. The anionic-anionic codoped La2Ti2O7 systems lower the band gap much more than their respective monodoping systems. Moreover, the electronic band positions of the doped systems with respect to the water oxidation/reduction potentials show that codoped (N-N, N-P, and C-S) systems are more promising candidates for visible-light photocatalysis. The calculated defect formation energy shows that the codoped systems are more stable than their respective monodoped systems.
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10.
  • Liu, Peng, et al. (författare)
  • Cationic-anionic mediated charge compensation on La2Ti2O7 for visible light photocatalysis
  • 2013
  • Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076. ; 15:40, s. 17150-17157
  • Tidskriftsartikel (refereegranskat)abstract
    • The cationic-anionic mediated charge compensation effect was studied in the layered perovskite La2Ti2O7 for the visible light photocatalysis. Our screened hybrid density functional study shows that the electronic structure of La2Ti2O7 can be tuned by the cationic (V, Nb, Ta)/anionic (N) mono-and co-doping. Such mono-doping creates impurity states in the band gap which helps the electron-hole recombination. But if the charge compensation is made by the cationic-anionic mediated co-doping then such impurity states can be removed and can be a promising strategy for visible light photocatalysis. The absolute band edge position of the doped La2Ti2O7 has been aligned with respect to the water oxidation/reduction potential. The calculated defect formation energy shows the stability of the co-doping system is improved due to the coulomb interactions and charge compensations effect.
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