Multi-electric field modulation for photocatalytic oxygen evolution: Enhanced charge separation by coupling oxygen vacancies with faceted heterostructures

A fundamental challenge of photocatalysis is developing efficient strategies to suppress the recombination of photogenerated charge carriers. Herein, ZnO/BiVO₄ hierarchical nanostructures were exemplified to demonstrate new concept of multi-electric field-assisted charge separation. The contribution of both facet engineering and defect modulation to the facilitated photocatalysis was confirmed by both experimental observations and theoretical calculations. Such integration of built-in fields in faceted BiVO₄ and anisotropic ZnO nanorods, together with the possible Z-scheme at the interfaces resulted into 1.36 mmol h⁻¹ g⁻¹ O₂ produced under visible light irradiation, and more than one order of magnitude enhanced apparent quantum yield at 450 nm. This work not only provides fundamental insights into the facet-dependent distribution of interfacial defects, but also offers a strategy for the design of faceted heterojunctions with controlled vacancies for significantly enhanced charge separation.