Synergistic effect of ZnMgAl-hydrotalcite nanomaterials electrocatalysts on high efficiency electrocatalytic reduction of CO2 to CO

Abstract

The excessive consumption of fossil fuels causes the increasing concentration of carbon dioxide (CO2) in the atmosphere. How to convert CO2 into various organic compounds and chemical fuels to promote the carbon cycle has become a hot issue in the forefront of science and technology in the world. In this paper, ZnMgAl-hydrotalcite (ZnxMg3-xAl-LDH, x=0, 1, 1.5, 2, 3) with different molar ratios of Zn, Mg and Al was prepared by hydrothermal synthesis method. Research results indicate that Zn1.5Mg1.5Al1-LDH with a molar ratio of n(Zn2+): n(Mg2+): n(Al3+) =1.5:1.5:1 on the layer of hydrotalcite has more appropriate metal ratio and arrangement, leading to the strongest synergistic effect among metals and demonstrating relatively optimal electrochemical performance. The Faraday efficiency of CO (FECO) preparation by CO2RR was up to 91.8% (-1.4V vs. RHE), which control the consumption within 9hours to less than 15%. The spin polarization density functional theory (DFT) method was used for calculation and structural analysis with the help of DMol3 module of Materials Studio. The results show that Zn1.5Mg1.5Al1-LDH has the lowest energy barrier of various reactions, the theoretical calculation results are consistent with the experimental results. Zn1.5Mg1.5Al1-LDH designed in this work has good catalytic activity and can be used for efficient electrocatalytic CO2 reduction to produce CO, realizing the resource utilization of CO2, and helping to improve the environmental problems caused by excessive CO2 emission. It provides a promising strategy for the environmental sciences to mitigate the effects of CO2.