Designing a type Ⅱ heterojunction ZnFe2O4/ ZnGa2O4 for photocatalytic reaction: Theoretical investigation

Energy shortages and environmental pollution are significant challenges in modern industries. Photocatalysts with a broad absorption spectrum, extended stability, superior charge separation efficiency, and strong redox capabilities exhibit considerable potential for addressing these issues. In this study, we designed a unique heterojunction photocatalyst composed of two semiconductors with staggered band structures: ZnFe2O4 (ZFO) and ZnGa2O4 (ZGO). This heterojunction facilitates the spatial separation of photogenerated carriers through the type II carrier transfer mechanism, thereby significantly prolonging their lifetime. Additionally, carrier separation enhances the formation of an internal electric field (IEF) at the interface, leading to enhanced photocatalytic quantum efficiency. Absorption and band structure analysis revealed that the band gap of the ZFO/ZGO heterojunction is 1.26 eV. Compared to pure ZFO and ZGO matrices, this heterojunction exhibits a "red-shifted" absorption edge and an enlarged optical response range. Furthermore, the ZFO/ZGO heterojunction displays semi-metallic characteristics that are advantageous for application-based control and retrieval, while inheriting the magnetic properties of ZFO. This strategy provides a new perspective to design photocatalysts.