| 1. |
- Hussain, Tanveer, et al.
(författare)
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Ab initio study of lithium-doped graphane for hydrogen storage
- 2011
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Ingår i: Europhysics letters. - 0295-5075. ; 96:2, s. 27013
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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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| 2. |
- Hussain, Tanveer, et al.
(författare)
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Calcium doped graphane as a hydrogen storage material
- 2012
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Ingår i: Applied Physics Letters. - 0003-6951. ; 100:18, s. 183902
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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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| 3. |
- Jiang, Xue, et al.
(författare)
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Graphene oxide as a chemically tunable 2-D material for visible-light photocatalyst applications
- 2013
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Ingår i: Journal of Catalysis. - 0021-9517. ; 299, s. 204-209
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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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| 4. |
- Kaewmaraya, Thanayut, et al.
(författare)
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Water adsorption on ZnO(10(1)over-bar0) : The role of intrinsic defects
- 2012
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Ingår i: Europhysics letters. - 0295-5075. ; 97:1, s. 17014
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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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| 5. |
- Liu, Peng, et al.
(författare)
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Hybrid density functional study on SrTiO3 for visible light photocatalysis
- 2012
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Ingår i: International journal of hydrogen energy. - Elsevier. - 0360-3199. ; 37:16, s. 11611-11617
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid Density Functional calculations have been performed on the electronic structure of anionic mono- (S, N, P, and C) and co-doped (N-N, N-P, N-S, P-P) SrTiO3 to improve their visible light photocatalytic activity. The electronic band position of doped system has been aligned with respect to the water oxidation/reduction potential. The electronic band position and optical absorption study shows that the mono- (S) and co-doped (N-N, N-P and P-P) SrTiO3 systems are promising materials for the visible-light photocatalysis. The calculated binding energies show that the co-doped systems are more stable than their respective mono-doped systems.
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| 6. |
- Liu, Peng, et al.
(författare)
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Layered Perovskite Sr2Ta2O7 for Visible Light Photocatalysis : A First Principles Study
- 2013
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Ingår i: The Journal of Physical Chemistry C. - 1932-7447. ; 117:10, s. 5043-5050
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Tidskriftsartikel (refereegranskat)abstract
- The layered perovskite Sr2Ta2O7 has been investigated for efficient visible light photocatalysis using the first principles study. The electronic structure of Sr2Ta2O7 is tuned by the anionic (N)/cationic (Mo, W) mono- and co-doping. Such doping creates impurity states in the band gap and therefore reduces the band gap significantly. The absolute band edge position of the doped Sr2Ta2O7 with respect to the water oxidation/reduction potential depends a lot on the p/d-orbital's energies of anionic/cationic dopants, respectively. The stability of the co-doped system is governed by the Coulomb interactions and charge compensation effects.
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| 7. |
- Nisar, Jawad, et al.
(författare)
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Hole mediated coupling in Sr2Nb2O7 for visible light photocatalysis
- 2012
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076. ; 14:14, s. 4891-4897
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Tidskriftsartikel (refereegranskat)abstract
- The band gap reduction and effective utilization of visible solar light are possible by introducing the anionic hole-hole mediated coupling in Sr2Nb2O7. By using the first principles calculations, we have investigated the mono-and co-anionic doping (S, N and C) in layered perovskite Sr2Nb2O7 for the visible-light photocatalysis. Our electronic structure and optical absorption study shows that the mono- (N and S) and co-anionic doped (N-N and C-S) Sr2Nb2O7 systems are promising materials for the visible light photocatalysis. The calculated binding energies show that if the hole-hole mediated coupling could be introduced, the co-doped systems would be more stable than their respective mono-doped systems. Optical absorption curves indicate that doping S, (N-N) and (C-S) in Sr2Nb2O7 can harvest a longer wavelength of the visible light spectrum as compared to the pure Sr2Nb2O7 for efficient photocatalysis.
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| 8. |
- Nisar, Jawad, et al.
(författare)
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Mo- and N-doped BiNbO(4) for photocatalysis applications
- 2011
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Ingår i: Applied Physics Letters. - 0003-6951. ; 99:5, s. 051909
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of pure BiNbO(4) has been calculated and their electronic band positions have been aligned with respect to the water oxidation/reduction potential. The effect of cationic (Mo), anionic (N), and co-doping (Mo-N) on BiNbO(4) has been studied and discussed with respect to the standard redox potential levels. Our results show that co-doping of Mo and N in BiNbO(4) reduces the band gap up to 31.8%, thus making it a potential candidate for the photocatalysis of water for hydrogen production. The relative stability between the mono-and co-doped BiNbO(4) materials show that co-doped material is more stable and feasible in comparison to the mono-doped materials.
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| 9. |
- Nisar, Jawad, et al.
(författare)
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Semiconducting allotrope of graphene
- 2012
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Ingår i: Nanotechnology. - 0957-4484. ; 23:38, s. 385704
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Tidskriftsartikel (refereegranskat)abstract
- From first-principles calculations, we predict a planar stable graphene allotrope composed of a periodic array of tetragonal and octagonal (4, 8) carbon rings. The stability of this sheet is predicted from the room-temperature molecular dynamics study and the electronic structure is studied using state-of-the-art calculations such as the hybrid density functional and the GW approach. Moreover, the mechanical properties of (4, 8) carbon sheet are evaluated from the Youngs modulus and intrinsic strength calculations. We find this is a stable planar semiconducting carbon sheet with a bandgap between 0.43 and 1.01eV and whose mechanical properties are as good as graphenes.
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| 10. |
- Pathak, Biswarup, et al.
(författare)
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Borane Derivatives : A New Class of Super- and Hyperhalogens
- 2011
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Ingår i: ChemPhysChem. - 1439-4235. ; 12:13, s. 2422-2427
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Tidskriftsartikel (refereegranskat)abstract
- Super- and hyperhalogens are a class of highly electronegative species whose electron affinities far exceed those of halogen atoms and are important to the chemical industry as oxidizing agents, biocatalysts, and building blocks of salts. Using the well-known Wade-Mingos rule for describing the stability of closo-boranes B(n)H(n)(2-) and state-of-the-art theoretical methods, we show that a new class of super-and hyperhalogens, guided by this rule, can be formed by tailoring the size and composition of borane derivatives. Unlike conventional superhalogens, in which a central metal atom is surrounded by halogen atoms, the superhalogens formed according to the Wade-Mingos rule do not have to have either halogen or metal atoms. We demonstrate this by using B(12)H(13) and its isoelectronic cluster CB(11)H(12) as examples. We also show that while conventional superhalogens containing alkali atoms require at least two halogen atoms, a single borane-like moiety is sufficient to give M(B(12)H(12)) clusters (M = Li, Na, K, Rb, Cs) superhalogen properties. In addition, hyperhalogens can be formed by using the above superhalogens as building blocks. Examples include M(B(12)H(13))(2) and M(CB(11)H(12))(2) (M = Li-Cs). This finding opens the door to an untapped source of superhalogens and weakly coordinating anions with potential applications.
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