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In Situ Formation of Oxygen Vacancies Achieving Near‐Complete Charge Separation in Planar BiVO 4 Photoanodes
Author(s) -
Wang Songcan,
He Tianwei,
Chen Peng,
Du Aijun,
Ostrikov Kostya Ken,
Huang Wei,
Wang Lianzhou
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202001385
Subject(s) - photocurrent , materials science , bismuth vanadate , oxygen evolution , optoelectronics , reversible hydrogen electrode , oxygen , electrode , water splitting , band gap , energy conversion efficiency , photocatalysis , catalysis , electrochemistry , chemistry , working electrode , biochemistry , organic chemistry
Abstract Despite a suitable bandgap of bismuth vanadate (BiVO 4 ) for visible light absorption, most of the photogenerated holes in BiVO 4 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 BiVO 4 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 BiVO 4 photoanodes. Upon loading NiFeO x 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.