Insight into the energy band alignment of magnetically separable Ag2O/ZnFe2O4 p-n heterostructure with rapid charge transfer assisted visible light photocatalysis

The fabrication of highly efficient catalysts with easy recyclability has received great attention in the development of realistic photocatalytic applications. Herein, a magnetically separable Ag2O/ZnFe2O4 p-n heterostructure photocatalyst was fabricated and utilized for the degradation of BPA under visible light irradiation. Results show that the obtained AZ-3 composite possesses the optimal performance, which is about 2.33-fold and 34.45-fold higher than that of Ag2O and ZnFe2O4, respectively. The enhanced performance is attributed to the rapid separation of photogenerated electrons and holes caused by the built-in electric field between p-type Ag2O and n-type ZnFe2O4, as detailedly evidenced by photoelectrochemical measurements. Moreover, density functional theory (DFT) calculations show that the electrons around the contact interface of Ag2O and ZnFe2O4 will be redistributed after their hybridization, while the investigation on energy band alignment further indicates that a type-II band alignment with ΔECBO = 0.16 eV and ΔEVBO = 0.65 eV is formed in this p-n heterostructure, which provides a solid support for the reaction mechanism. This work gives deep insights into the charge transfer properties of p-n heterostructure systems and opens new vistas for the construction of highly efficient and magnetically separable photocatalysts.