Enhanced photocatalytic performances and magnetic recovery capacity of visible-light-driven Z-scheme ZnFe ₂ O ₄ /AgBr/Ag photocatalyst

High efficiency, high stability and easy recovery are three key factors for practical photocatalysts. Z-scheme heterostructure is one of the most promising photocatalytic systems to meet all above requirements. However, efficient Z-scheme photocatalysts which could absorb visible light are still few and difficult to implement at present. In this work, the composite photocatalysts ZnFe ₂ O ₄ /AgBr/Ag were prepared through a two-step method. A ∼92% photodegradation rate on methyl orange was observed within 30 min under visible light, which is much better than that of individual ZnFe ₂ O ₄ or AgBr/Ag. The stability was also greatly improved compared with AgBr/Ag. The increased performance is resulted from the suitable band alignment of ZnFe ₂ O ₄ and AgBr, and it is defined as Z-scheme mechanism which was demonstrated by detecting active species and electrochemical impedance spectroscopy. Besides, ZnFe ₂ O ₄ /AgBr/Ag is ferromagnetic and can be recycled by magnet. These results show that ZnFe ₂ O ₄ /AgBr/Ag is a potential magnetically recyclable photocatalyst which can be driven by visible light.