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

CO 2 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 Zn 3 V 2 O 8 as a phase transformation material, we construct an effective Zn 2 V 2 O 7 /Zn 3 V 2 O 8 /ZnO (OVZn) Z-scheme system by partial decomposition of Zn 3 V 2 O 8 into Zn 2 V 2 O 7 and ZnO. Time-resolved fluorescence decay (TRFD) spectra investigation shows that the photogenerated electrons of Zn 2 V 2 O 7 and ZnO recombine with the holes of Zn 3 V 2 O 8 , retaining more reductive electron of Zn 3 V 2 O 8 for CO 2 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 CO 2 reduction. OVZn and metal loaded OVZn have better photocatalytic performance, showing application superiority on CO 2 photoreduction.