Highly efficient visible light-driven Ag/AgBr/ZnO composite photocatalyst for degrading Rhodamine B

In this paper, Ag/AgBr/ZnO composites have been successfully synthesized by two steps of deposition–precipitation method, then followed by reduction under visible light irradiation. The results of X-ray diffraction and X-ray photoelectron spectroscopy confirmed Ag/AgBr nanoparticles were loaded on ZnO support. The transmission electron microscopy showed Ag/AgBr nanoparticles with small sizes of 5 nm were well attached on the surface of ZnO, which made Ag/AgBr/ZnO composites display strong absorption in the visible light range. Ag/AgBr/ZnO composites showed much better photocatalytic activities for degradation of Rhodamine B dye under visible light than pure ZnO. The enhanced photocatalytic activity may be ascribed to the synergetic effects including enhanced visible light absorption, narrowed band gap and effective separation of photogenerated electron–hole pairs. In addition, catalytic repetitive tests showed that Ag/AgBr/ZnO composite maintained good stability and the activity decreased slightly after 10 cycles. The possible mechanism was tentatively proposed based on the photoluminescence spectra and the reaction effects by adding the radical scavengers.