Faster Kinetics and High Selectivity for Electrolytic Reduction of CO2 with Zn0/Zn2+ Interface of ZnO/ZnAl2O4 Derived from Hydrotalcite

The conversion of carbon dioxide to chemical raw materials or high value-added products can utilize the abundant carbon resources in nature as well as mitigate the greenhouse effect caused by excess carbon dioxide in the atmosphere. The electrocatalytic reduction of carbon dioxide process suffers from the problems of low product selectivity, low current efficiency, and poor electrode stability, and thus its application has been affected to some extent. In this study, bulk zinc-aluminum hydrotalcite (ZnAl-LDH) was prepared by the co-precipitation method, and the activity towards CO2 reduction was limited due to the stacking of the laminae, which led to the overlap of active sites. The electrochemical impedance was large and the electron transfer ability was poor, so it was thermally modified by means of calcination at different temperatures. Combined with the thermal stability of hydrotalcite, three representative temperatures, 300celcius, 500celcius and 900celcius were selected, and the derived oxides obtained under calcination had different structures and thus possessed different activities towards CO2RR. Through electrochemical and physical characterizations, it was found that the ZnAl-LDH calcined at 900celcius was highly active for the electrocatalytic reduction of carbon dioxide, and the Faraday efficiency of carbon monoxide (FECO) of this material reached as high as 93% at a voltage of -1.05 V (vs RHE) with excellent electrochemical stability.