Investigation of CO2 photoreduction mechanism over the Zn2V2O7/Zn3V2O8/ZnO Z-scheme system

CO2 photoreduction under mild conditions remains challenging, attributing to sluggish kinetics of complex coupling process of multi-electrons-protons and inefficient electron-hole pairs utilization. Herein, with Zn3V2O8 as a phase transformation material, we construct an effective Zn2V2O7/Zn3V2O8/ZnO (OVZn) Z-scheme system by partial decomposition of Zn3V2O8 into Zn2V2O7 and ZnO. Time-resolved fluorescence decay (TRFD) spectra investigation shows that the photogenerated electrons of Zn2V2O7 and ZnO recombine with the holes of Zn3V2O8, retaining more reductive electron of Zn3V2O8 for CO2 reduction. Moreover, in-situ Fourier-transform infrared spectroscopy suggests that the heterostructure can lower the energy barrier of CO desorption by changing bridge -bonded CO to linear-bonded CO and optimizing the energy barrier of CO production. Moreover, Cu, Ag and Au loading on OVZn greatly enhance light harvesting and promote photoelectric conversion, producing much photogenerated electron-hole pairs for CO2 reduction. OVZn and metal loaded OVZn have better photocatalytic performance, showing application superiority on CO2 photoreduction.