p-n Characteristic Tuning of Bi-based Oxyhalide Photocatalyst and its Application to Photoelectrochemical Reaction

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19084
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 36:Inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Tomita Osamu 京都大学, 工学研究科, 助教 (40801303)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 光電気化学 / 光触媒 / 光エネルギー / アニオン交換

Outline of Final Research Achievements

Controlling carrier density of semiconductors has been known as one of the effective ways to change the diffusion lengths of photoexcited carriers and thereby improve their photocatalytic activity. In the present study, particle of BiOBr doped with varied amounts of Cl were prepared in order to investigate the relation between the total amount of halide anions and the donor density in the products. Although the photoelectrode of undoped BiOBr showed a photoanodic current, those consisting of Cl-doped BiOBr showed both the photoanodic and photocathodic current, implying that the Cl-doping successfully reduced the donor density of original n-type BiOBr. The BiOBr doped with a suitable amount of Cl exhibited superior activity for O2 evolution (half reaction) compared to BiOBr under ultraviolet and visible light irradiation. The improved activity suggested the potential of this carrier density control strategy for improving the efficiency of photocatalysis on these oxyhalide materials.

Free Research Field

光電気化学，光触媒

Academic Significance and Societal Importance of the Research Achievements

半導体光触媒および光電極の開発が盛んに進められており，光キャリアの有効利用に向けて，半導体光触媒材料の長波長化，表面反応促進のための表面修飾などの検討がなされている．本課題では，層状酸ハロゲン化物を例に，光電極性能，光触媒活性に与える，イオン半径の小さなハロゲンの合成時の過剰添加効果を検討した．アニオン交換あるいはアニオン補填によるドナー密度制御を可能とし，これに加えて，本手法が懸濁系光触媒活性の向上にも有効な戦略の1つになることを示した．このことは，新しい特性や機能の発現させるための１つの方法に繋がるといえ，物性制御法の1つを示したことに意義があるといえる．