Enhancing photoelectrochemical performance by effectively managing the density of oxygen vacancies in CuO/BiVO4 composites

Abstract

In this study, we deliberately introduced oxygen vacancies into BiVO₄ through a hydrogenation treatment, followed by the deposition of p-type CuO onto its surface using spin coating. This process resulted in the formation of a BiVO₄/CuO p–n heterostructure. By varying the hydrogenation temperature, we were able to control the concentration of oxygen vacancies in BiVO₄ and examine their impact on optical properties and PEC performance. The PEC test results revealed that the oxygen vacancy-rich BiVO₄/CuO heterostructure exhibited improved PEC performance. This enhancement can be primarily attributed to the improved separation and transport efficiency of charge carriers, facilitated by the presence of oxygen vacancies. Furthermore, the establishment of a type-II band structure optimized the band alignment, leading to enhanced visible light absorption and more effective utilization of photogenerated charge carriers. In summary, our dual modification strategy, which effectively integrates hydrogenation-induced oxygen vacancy engineering with p–n heterostructure formation using CuO, offers significant potential for advancing high-efficiency PEC electrode applications.