Effect of Halogen on the Morphology Regulation of Cd-BTC and the Performance of Electrocatalytic Reduction of CO2 to CO.

Electrocatalysis is an efficient method for reducing greenhouse gas emissions and producing high-value chemicals. Metal-organic materials are currently popular materials to improve the catalytic performance of the electrocatalytic CO2 reduction reaction (CO2RR), but due to their inherent conductivity and poor internal active sites, direct application is challenging. Halogens have potential advantages in regulating the activity of carbon dioxide reduction reactions, but they have not yet been directly applied in the practical use of Cd-based electrocatalysts. In this paper, Cd-1,3,5-benzenetricarboxylic acid (Cd-BTC) was prepared by the solvothermal method, and halogen atoms were introduced into Cd-BTC materials to obtain halogen-containing X-Cd-BTC (X = F, Cl, Br, and I) catalysts. Their electrocatalytic CO2RR activity changed significantly with the electronegativity of halogen. Among them, the CO faradaic efficiency (FECO) of the best Cl-Cd-BTC catalyst was as high as 97.2% at the potential of -1.3 V versus reversible hydrogen electrode (vs. RHE), and the FECO remained above 93% after 25,200 s stability test. It showed that the introduction of halogen Cl- will lead to strong electronic interaction between Cl- and Cd2+, which will accelerate the reaction kinetics, thus significantly improving the electrocatalytic efficiency of Cd-BTC. This catalyst is expected to efficient electrochemical CO2 to CO.