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Keywords = BiVO4 (110) facet

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12 pages, 4193 KB  
Article
Oxygen-Vacancy-Induced Enhancement of BiVO4 Bifunctional Photoelectrochemical Activity for Overall Water Splitting
by Huailiang Fu, Qingxiu Qi, Yushu Li, Jing Pan and Chonggui Zhong
Nanomaterials 2024, 14(15), 1270; https://doi.org/10.3390/nano14151270 - 29 Jul 2024
Cited by 9 | Viewed by 2973
Abstract
Hydrogen generation via photoelectrochemical (PEC) overall water splitting is an attractive means of renewable energy production so developing and designing the cost-effective and high-activity bifunctional PEC catalysts both for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) has been focused [...] Read more.
Hydrogen generation via photoelectrochemical (PEC) overall water splitting is an attractive means of renewable energy production so developing and designing the cost-effective and high-activity bifunctional PEC catalysts both for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) has been focused on. Based on first-principles calculations, we propose a feasible strategy to enhance either HER or OER performance in the monoclinic exposed BiVO4 (110) facet by the introduction of oxygen vacancies (Ovacs). Our results show that oxygen vacancies induce charge rearrangements, which enhances charge transfer between active sites and adatoms. Furthermore, the incorporation of oxygen vacancies reduces the work function of the system, which makes charge transfer from the inner to the surface more easily; thus, the charges possess stronger redox capacity. As a result, the Ovac reduces both the hydrogen adsorption-free energy (ΔGH*) for the HER and the overpotential for the OER, facilitating the PEC activity of overall water splitting. The findings provide not only a method to develop bifunctional PEC catalysts based on BiVO4 but also insight into the mechanism of enhanced catalytic performance. Full article
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12 pages, 1928 KB  
Article
Electronic Characteristics, Stability and Water Oxidation Selectivity of High-Index BiVO4 Facets for Photocatalytic Application: A First Principle Study
by Zhiyuan Zhang, Yuqi Xiang and Zhihong Zhu
Nanomaterials 2023, 13(13), 2023; https://doi.org/10.3390/nano13132023 - 7 Jul 2023
Cited by 2 | Viewed by 2370
Abstract
Some high-index facets of BiVO4, such as (012), (210), (115), (511), (121), (132) and (231), exhibit much better photocatalytic performance than conventional (010) and (110) surfaces for water splitting. However, the detailed mechanisms and stability of improved photocatalytic performance for these [...] Read more.
Some high-index facets of BiVO4, such as (012), (210), (115), (511), (121), (132) and (231), exhibit much better photocatalytic performance than conventional (010) and (110) surfaces for water splitting. However, the detailed mechanisms and stability of improved photocatalytic performance for these high-index BiVO4 surfaces are still not clear, which is important for designing photocatalysts with high efficiency. Here, based on first principle calculation, we carried out a systematic theoretical research on BiVO4 with different surfaces, especially high-index facets. The results show that all of the high-index facets in our calculated systems show an n-type behavior, and the band edge positions indicate that all of the high-index facets have enough ability to produce O2 without external bias. Electronic structures, band alignments and formation enthalpy indicate that (012), (115) and (132) could be equivalent to (210), (511) and (231), respectively, in the calculation. Oxidation and reduction potential show that only (132)/(231) is stable without strongly oxidative conditions, and the Gibbs free energy indicates that (012)/(210), (115)/(511), (121) and (132)/(231) have lower overpotential than (010) and (110). Our calculation is able to unveil insights into the effects of the surface, including electronic structures, overpotential and stability during the reaction process. Full article
(This article belongs to the Special Issue First-Principle Calculation Study of Nanomaterials)
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15 pages, 4292 KB  
Article
Au@CoS-BiVO4 {010} Constructed for Visible-Light-Assisted Peroxymonosulfate Activation
by Yekun Ji, Ye Zhou, Jinnan Wang, Aimin Li, Weilin Bian and Philippe François-Xavier Corvini
Catalysts 2021, 11(11), 1414; https://doi.org/10.3390/catal11111414 - 22 Nov 2021
Cited by 12 | Viewed by 3178
Abstract
A visible-light-Fenton-like reaction system was constructed for the selective conversion of peroxymonosulfate to sulfate radical. Au@CoS, when doped on monoclinic BiVO4 {010} facets, promoted spatial charge separation due to the different energy band between the m-BiVO4 {010} and {110} facets. The [...] Read more.
A visible-light-Fenton-like reaction system was constructed for the selective conversion of peroxymonosulfate to sulfate radical. Au@CoS, when doped on monoclinic BiVO4 {010} facets, promoted spatial charge separation due to the different energy band between the m-BiVO4 {010} and {110} facets. The visible-light response of m-BiVO4 was enhanced, which was attributed to the SPR effect of Au. And the photogenerated electrons were transferred from the m-BiVO4 {010} facet to Au via a Schottky junction. Owing to higher work function, CoS was able to capture these photoelectrons with acceleration of the Co(Ⅱ)/Co(Ⅲ) redox, enhancing peroxymonosulfate conversion to sulfate radical (Co2+ + HSO5→ Co3+ + •SO4 + OH). On the other hand, holes accumulated on m-BiVO4 {110} facets also contributed to organics oxidation. Thus, more than 95% of RhB was degraded within 40 min, and, even after five cycles, over 80% of RhB could be removed. The radical trapping experiments and EPR confirmed that both the sulfate radical and photogenerated hole were the main species for organics degradation. UV-vis DRS, photoluminescence (PL) and photoelectrochemical analyses also confirmed the enhancement of the visible-light response and charge separation. In a pilot scale experiment (PMS = 3 mM, initial TOC = 151 mg/L, reaction time = 4 h), CoS-Au-BiVO4 loaded on glass fiber showed a high mineralization rate (>60%) of practical wastewater. Full article
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