Band Engineering of Photocatalytic BiVO 4 with Modified Vanadium States via Potassium Chloride Addition during Hydro-Thermal Synthesis and Post-Annealing

Sopheak Meng, Takaya Ogawa, Keiichi N. Ishihara and Hideyuki Okumura ()
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Sopheak Meng: Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
Takaya Ogawa: Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
Keiichi N. Ishihara: Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
Hideyuki Okumura: Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan

Energies, 2023, vol. 16, issue 2, 1-16

Abstract: The monoclinic BiVO 4 in a powder state was prepared via a hydrothermal method, with the addition of KCl as a structure-directing agent. The as-prepared sample was calcined at different temperatures (400–600 °C), either in the air or in Ar gas. It is found that, though the morphology and crystal structure mostly remain unchanged, the bandgap properties are modified during calcination. A detailed analysis of the surface chemical states and optical absorption properties reveals the involvement of tetravalent vanadium ions and oxygen vacancies as the cause of the band modification. The bandgap properties are to be found tunable via changing the calcination condition, as well as the KCl concentration in the precursor. The photocatalytic properties of BiVO 4 samples are greatly enhanced with the addition of KCl in the precursor, but degraded by post-annealing, where the residual Cl in the calcined sample may act as an inhibitor. The enhanced photoactivity is explained in terms of favorable faceting, bandgap modification, and heterojunction of BiVO 4 /BiOCl.

Keywords: BiVO 4; tetravalent vanadium; oxygen vacancies; potassium chloride; bandgap (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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