Enhancing the Photoactivity of Faceted BiVO₄ via Annealing in Oxygen‐Deficient Condition

Abstract

Thermal annealing of metal oxides in oxygen‐deficient atmosphere, particularly reducing hydrogen gas, has been demonstrated to induce oxygen vacancy formation for enhanced photoactivity of the materials. Here, it is demonstrated that argon annealing (another prevalently used oxygen‐deficient gas) in the temperature range of 300–700 °C greatly affects the activity of dual‐faceted BiVO4 microcrystals for photocatalytic O2 generation and photocurrent generation. While treatment at 300 °C has little to no effect, higher temperatures of 500 and 700 °C significantly improve the crystallinity, alter the local structure distortion, and reduce the bandgap energy of the treated BiVO4. The higher temperature treatment also favors formation of new subgap states attributed to oxygen vacancies, as supported by surface photovoltage and electron paramagnetic resonance spectroscopies. Despite the most profound improvements in structural, optical, and electronic properties displayed by the 700 °C‐treated BiVO4, the sample annealed at 500 °C exhibits the highest photoactivity. The lower activity of the 700 °C‐treated BiVO4 is ascribed to the creation of bismuth vacancies and the loss of well‐defined crystal facets, contributing to impeded electron transport and poor charge separation.

Investigating the Role of Oxygen Vacancies and Lattice Strain Defects on the Enhanced Photoelectrochemical Property of Alkali Metal (Li, Na, and K) Doped ZnO Nanorod Photoanodes

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Synthesis of Silicate‐Bridged Heterojunctional SnO2/BiVO4 Nanoplates as Efficient Photocatalysts to Convert CO2 and Degrade 2,4‐Dichlorophenol

“…Therefore, it is obliged to develop the visible‐light‐responsible photocatalysts to maximally utilize the solar energy . With a narrow bandgap energy, bismuth vanadate (BiVO 4 ) is capable of absorbing the solar light in the visible range, hence could act as an ideal visible‐light‐responsive photocatalyst . The photocatalytic performance of BiVO 4 is still limited due to the small surface area and fast charge recombination.…”

Strong Light–Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO4 for Photoelectrochemical Water Splitting

“…The effect of oxygen vacancies on the BiVO 4 PEC performance is still under debate in the literature. Recent works indicate that oxygen vacancies can have multiple roles on the PEC‐WS performance of metal oxides . From the positive side, it is commonly accepted that oxygen vacancies inside the bulk medium improve the free carrier concentration and consequently lead to better charge carrier transport .…”