Electron-buffer-mediated dual Z-scheme ZnSe/Ag2Se/AgBr heterojunction for efficient CO2 photocatalytic reduction

Design of photocatalysts with high-efficiency for sunlight utilization is one of the prerequisites for CO 2 photoreduction . Besides, modulating a stable electron-donating environment to meet the energy barrier for CO 2 reduction to CO is crucial. In this work, the ZnSe/Ag 2 Se/AgBr (ZAA) heterojunction was fabricated by growing the ZnSe on the AgBr surface accompanied by in-situ generation of Ag 2 Se between the two components by hydrothermal process. Results showed that the ZAA exhibited excellent light response ability over the full wavelength range. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) demonstrated that the charge transfer of the ZAA conformed to dual Z-scheme mechanism, with the Ag 2 Se acting as an electron transfer bridge, which in turn acted as an electron reservoir to accelerate electron transfer, facilitating carriers’ separation. The highest CO yield of 54.14 µmol/g/h was obtained from the optimal ZAA-2, which was 11.76 and 10.44 times of pure ZnSe and Ag 2 Se, respectively. This work demonstrated the feasibility of a dual Z-scheme heterostructure with full spectrum response for offering stable electron-donating environment and improving electron transfer for enhanced photocatalytic activity.