Electronic structure and optical properties of monoclinic clinobisvanite BiVO4

Zhao, Zong‐Yan; Li, Zhaosheng; Zou, Zhigang

doi:10.1039/c0cp01871f

Cited by 348 publications

(353 citation statements)

References 42 publications

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“…The selected k-points of (L-M-A-Γ-Z) were employed in previous studies. 42 The band gap type was found to be indirect in line with previous reports. 43,44 Figure S2 (with x = 0.0625) has given a reduced band gap with a value around 2.3 eV (Figure 4c), which is very close to the experimentally reported ones.…”

Section: Electronic Structure Propertiessupporting

confidence: 79%

Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory

2018

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The effects of intrinsic defects in monoclinic bismuth vanadate (BiVO 4 ) on its stability and optoelectronic properties for photochemical water splitting application were examined using density functional theory (DFT). Among the most favorable structures, only that associated with V-antisites on Bi with additional Bi-vacancies (Bi (1-5x) V (1+3x) O 4 with x = 0.0625) revealed narrower band gap energy by 0.5 eV compared to pristine material (calculated value is 2.8 eV) giving a value of 2.3 eV, which is very close to the experimentally reported ones (in the 2.4-2.5 eV range). The low electron mobility reported experimentally for this material was also confirmed by the relatively large electron effective masses obtained for the intrinsic defective Bi (1-5x) V (1+3x) O 4 (x = 0.0625) structure along the three principal crystallographic directions. The strongly localized nature of the accommodated electrons on the d-orbitals of the newly

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Section: Electronic Structure Propertiessupporting

confidence: 79%

Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory

2018

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“…Assuming that the internal quantum yield of electron-hole generation approaches 100% and no charge carrier recombination has taken place within the response time of the setup, the carrier mobility () and the carrier lifetime () can be obtained from the peak and the decay of the TRMC signal, respectively. [17,40] [43] , the individual electron (e) and hole mobility (h) of each films can be calculated ( Table 1). The carrier lifetime, however, shows a much larger change and increases from 43 ns to 109 ns.…”

Section: Resultsmentioning

confidence: 99%

Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through Mild Hydrogen Treatment

Jang

Friedrich

Müller

et al. 2017

Advanced Energy Materials

122

164

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Widespread application of solar water splitting for energy conversion is largely dependent on the progress in developing not only efficient, but also cheap and scalable photoelectrodes. Metal oxides, which can be deposited with scalable techniques and are relatively cheap, are particularly interesting, but high efficiency is still hindered by the poor carrier transport properties (i.e., carrier mobility and lifetime). In this paper, a mild hydrogen treatment is introduced to bismuth vanadate (BiVO4), which is one of the most promising metal oxide photoelectrodes, as a method to overcome the carrier transport limitations. Timeresolved microwave and terahertz conductivity measurements reveal more than two-fold enhancement of the carrier lifetime for the hydrogen-treated BiVO4, without significantly affecting the carrier mobility. This is in contrast to the case of tungsten-doped BiVO4, although hydrogen is also shown to be a donor type dopant in BiVO4. The enhancement in carrier lifetime is found to be caused by significant reduction of trap-assisted recombination, either via passivation of deep trap states or reduction of trap state density, which can be related to vanadium anti-site on bismuth or vanadium interstitials according to density functional theory calculations. Overall, these findings provide further insights on the interplay between defect modulation and carrier transport in metal oxide photoelectrodes, which will benefit the development of low-cost, highly-efficient solar energy conversion devices.

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“…The resulting band structures shown in Figure 6 are in good qualitative agreement with previous DFT results. [54][55][56] The conduction band displays several nearly degenerate local minima and is dominated by localized V 3d states, whereas the valence band is dominated by hybridized Bi 6s and O 2p states. Along the symmetry path, the band gap is sustained between points along the Γ-V segment and Z.…”

Section: Understanding Distortion-dependent Transportmentioning

confidence: 99%

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

Newhouse

Guevarra

Umehara

et al. 2018

Energy Environ. Sci.

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Improving the efficiency of solar-power oxygen evolution is both critical for development of solar fuels technologies and challenging due to the broad set of properties required of a solar fuels photoanode. Bismuth vanadate, in particular the monoclinic clinobisvanite phase, has received substantial attention and has exhibited the highest radiative efficiency among metal oxides with a band gap in the visible range. Efforts to further improve its photoelectrochemical performance have included alloying one or more metals onto the Bi and/or V sites, with progress on this frontier stymied by the difficulty in computational modelling of substitutional alloys and the high dimensionality of co-alloying composition spaces. Since substituional alloying simultaneously changes multiple materials properties, understanding the underlying cause for performance improvements is also challenging, motivating our application of combinatorial materials science techniques to map photoelectrochemical performance of 948 unique bismuth vanadate alloy compositions comprising 0 to 8% alloys of P, Ca, Mo, Eu, Gd, and W along with a variety of compositions from each pairwise combination of these elements. Upon identification of substantial improvements in the (Mo,Gd) co-alloying space, structural mapping was performed to reveal a remarkable correlation between performance and a lowered monoclinic distortion. First-principles density functional theory calculations indicate that the improvements are due to a lowered hole effective mass and hole polaron formation energy, and collectively, our results identify the monoclinic distortion as a critical parameter in the optimization and understanding of bismuth vanadate-based photoanodes. IntroductionThe production of fuels via photoelectrochemistry (PEC) has been recognized as a promising method for capturing and storing intermittent solar energy, in particular as renewable transportation fuels. 1 Regardless of the fuel to be generated, the oxygen evolution reaction at the photoanode is critical; hence development of stable, efficient, n-type semiconductors composed of earth abundant elements and producible by scalable, cost-effective methods has received increasing research attention. [2][3][4] Bismuth vanadate, BiVO4, in particular has become the oxide semiconductor serving as the platform to develop and demonstrate a toolkit of techniques for improving and understanding the fundamental properties and photoelectrochemical performance of novel oxide-based semiconductors, despite its non-optimal bandgap. 2,5 As recently reviewed, the methods of improving the properties include heterojunction formation, alloying or doping, hydrogen or nitrogen annealing, nanostructuring to enhance charge collection, microstructuring for photon management, and surface coating to passivate surface defects and enhance catalysis. 3,4,[6][7][8][9] The highest performing BVO-based photoanodes reported to date have all incorporated several of these strategies in order to produce photocurrent densities in the range of app...

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Electronic structure and optical properties of monoclinic clinobisvanite BiVO4

Cited by 348 publications

References 42 publications

Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory

Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory

Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through Mild Hydrogen Treatment

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

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Electronic structure and optical properties of monoclinic clinobisvanite BiVO4

Cited by 348 publications

References 42 publications

Determination of the Intrinsic Defect at the Origin of Poor H2 Evolution Performance of the Monoclinic BiVO4 Photocatalyst Using Density Functional Theory

Determination of the Intrinsic Defect at the Origin of Poor H2 Evolution Performance of the Monoclinic BiVO4 Photocatalyst Using Density Functional Theory

Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through Mild Hydrogen Treatment

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

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Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory

Determination of the Intrinsic Defect at the Origin of Poor H₂ Evolution Performance of the Monoclinic BiVO₄ Photocatalyst Using Density Functional Theory