Enhancing the performance of Bi2O3–ZnO semiconductor bilayers for photoelectrochemical electrodes by strategically engineering oxygen vacancies

This study successfully synthesized sheet-like triangular Bi2O3 using the hydrothermal method and subsequently annealed it in a hydrogen-contained atmosphere to effectively introduce oxygen vacancies. ZnO was fabricated through sputtering at elevated substrate temperatures, which also facilitated the formation of oxygen vacancies. We prepared Bi2O3/ZnO composites to assess their performance in photoelectrochemical (PEC) and photocatalytic applications under illumination. Oxygen vacancies significantly enhance the materials' charge separation capabilities, resulting in increased photocurrent density and reduced interfacial resistance while also boosting the number of surface active sites. Furthermore, control over the annealing conditions and substrate temperatures can optimize the generation of oxygen vacancies, thereby enhancing the performance of the composites. Introducing oxygen vacancies and establishing a Z-scheme structure in Bi2O3 and ZnO represent effective strategies for advancing the potential applications of oxide semiconductor composites in PEC electrodes.