Construction of Z-scheme Cu2O/Cu/AgBr/Ag photocatalyst with enhanced photocatalytic activity and stability under visible light

A series of Cu2O/Cu/AgBr/Ag photocatalysts were synthesized by a redox procedure followed by photo-assisted deposition. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the structure of the system. It is found that Cu nanoparticles (NPs) could be controllable to grow in between Cu2O and AgBr. Without Cu NPs between Cu2O/AgBr, under visible light irradiation for 50 min, only a low photocatalytic degradation of methyl orange (MO) (∼51%) was observed compared with the high MO photodegradation (∼98%) in the presence of Cu NPs. Furthermore, introducing Cu NPs assists in accelerating excited carrier transfer at the interface between Cu2O and AgBr, measured by the photoluminescence spectra, photocurrent and electrochemical impedance spectra, which thus helps to increase the stability of the photocatalyst. The increased photocatalytic activity and stability can be attributed to the favorable band alignment between Cu2O and AgBr mediated by Cu NPs, which is known as the Z-scheme mechanism and confirmed by the detection of the active species. These results demonstrate that the Cu2O/Cu/AgBr/Ag is a potential visible light photocatalyst for pollutants degradation.