Efficient Activation and Electroreduction of Carbon Dioxide on an Electrocatalyst Cadmium Carbonate

Electrochemical reduction of carbon dioxide (CO2) opens up possibilities toward the formation of value-added products, while CO2 reduction performance remains largely restricted in view of low energy efficiency and poor product selectivity due to the sluggish kinetics for the catalysts to initiate CO2 activation and C═O bond breaking. Here, we for the first time report a trigonal crystal otavite cadmium carbonate (CdCO3) as an electrocatalyst with excellent performance for efficient activation and further electrochemical reduction of CO2. It exhibits high selectivity for a CO product at a limited low potential range and reaches the highest Faradaic efficiency of 90% with a low overpotential of 250 mV in a 0.1 M KHCO3 solution. By combining the density functional theory (DFT) calculation and the Fourier transform infrared spectroscopy, it is suggested that, in addition to the strong affinity (binding energy ∼−3.55 eV) of the molecular CO2 onto a CdCO3 surface, the CO2 activation to lower the key intermediate CO2·– formation potential with the help of a CO2–CdCO3 interaction could be mainly contributed to its high selectivity for CO2 reduction toward CO. Furthermore, the existence of the key intermediate CO2·– during the CO2 reduction process was experimentally confirmed by in situ ultraviolet–visible absorption spectroscopy characterization. The catalyst described here may provide a promising direction for the development of practical catalysts for electrolytic fuel synthesis.