In Situ Formation of Oxygen Vacancies Achieving Near‐Complete Charge Separation in Planar BiVO4 Photoanodes

Despite a suitable bandgap of bismuth vanadate (BiVO4) for visible light absorption, most of the photogenerated holes in BiVO4 photoanodes are vanished before reaching the surfaces for oxygen evolution reaction due to the poor charge separation efficiency in the bulk. Herein, a new sulfur oxidation...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2020-07, Vol.32 (26), p.e2001385-n/a
Main Authors: Wang, Songcan, He, Tianwei, Chen, Peng, Du, Aijun, Ostrikov, Kostya (Ken), Huang, Wei, Wang, Lianzhou
Format: Article
Language:English
Subjects:
Bismuth oxides
bismuth vanadate
Carrier density
Charge density
Charge efficiency
charge separation
Chlorophyll
Current carriers
Current efficiency
Efficiency
Electromagnetic absorption
Heat treatment
Hydrogen production
Materials science
Oxidation
Oxygen evolution reactions
oxygen vacancies
Photoanodes
Photoelectric effect
Photoelectric emission
Separation
Vacancies
Vanadates
water splitting
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Summary:Despite a suitable bandgap of bismuth vanadate (BiVO4) for visible light absorption, most of the photogenerated holes in BiVO4 photoanodes are vanished before reaching the surfaces for oxygen evolution reaction due to the poor charge separation efficiency in the bulk. Herein, a new sulfur oxidation strategy is developed to prepare planar BiVO4 photoanodes with in situ formed oxygen vacancies, which increases the majority charge carrier density and photovoltage, leading to a record charge separation efficiency of 98.2% among the reported BiVO4 photoanodes. Upon loading NiFeOx as an oxygen evolution cocatalyst, a stable photocurrent density of 5.54 mA cm−2 is achieved at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5 G illumination. Remarkably, a dual‐photoanode configuration further enhances the photocurrent density up to 6.24 mA cm−2, achieving an excellent applied bias photon‐to‐current efficiency of 2.76%. This work demonstrates a simple thermal treatment approach to generate oxygen vacancies for the design of efficient planar photoanodes for solar hydrogen production. A new sulfur oxidation process is developed to synthesize planar BiVO4 thin films with in‐situ‐formed oxygen vacancies in the whole film, achieving a record charge‐separation efficiency of 98.2%. By depositing an efficient NiFeOx oxygen evolution cocatalyst, a high and stable photocurrent density of 5.54 mA cm−2 for photoelectrochemical water splitting is achieved.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202001385