Enhancing Photocatalytic Degradation via the Synergetic Effect of Vacancies and Built-In Potential in a BiOCl/BiVO₄ p–n Heterojunction

Photoinduced charge separation and surface reactions are essential for ensuring high quantum efficiency of the photochemical and photophysical processes. BiVO₄-based heterojunctions are promising materials for high-performance photocatalysts; however, their photocatalytic performance is significantly lower than the theoretical limit due to the sluggish water oxidation dynamics and rapid recombination of charge carriers on the catalyst surface. To address these issues, oxygen vacancies (OVs) are introduced to a rationally designed BiVO₄-based heterojunction using built-in potential and gradient OVs to promote the separation of carriers and increase the photocatalytic activity. The heterojunctions with OVs exhibit a 2-fold increase in the photocatalytic activity for phenol degradation compared with that of pristine BiVO₄. Additionally, density functional theory is applied to elucidate the synergistic mechanism of light absorption and charge separation in BiOCl/BiVO₄ p–n heterojunction photocatalysts containing vacancies. The obtained results demonstrate a synergistic effect of vacancies and the built-in potential, providing a pathway for defect engineering in photocatalytic processes.