Cu/CdCO3 catalysts for efficient electrochemical CO2 reduction over the wide potential window

High efficiency and low-cost catalyst-driven electrocatalytic CO2 reduction to CO production are of great significance for energy storage and development. The severe competitive hydrogen evolution reaction occurs at large negative potential window limits the achievement of the target product from CO2 at high efficiency. Here, we successfully prepared Cux/CdCO3 composite catalyst rich in interfaces, in which achieved high CO Faraday efficiency exceeded 90% in a wide potential window of 700 mV and highest value up to 97.9% at −0.90 V vs. RHE. The excellent performance can be ascribed to the positive contribution of Cux/CdCO3, which maintains a suitable high local pH value during electrochemical reduction, thus inhibiting the competitive hydrogen evolution reaction. Moreover, the compact structure between Cu and CdCO3 ensures fast electron transfer both inside catalysts and interface, thus speeding up the reaction kinetics of CO2 to CO conversion. Theoretically calculations further prove that the combination of Cu and CdCO3 provides the well-defined electronic structure for intermediates adsorption, significantly reducing the reaction barrier for the formation of CO. This work provides new insights into the design of efficient electrochemical CO2 reduction catalysts for inhibiting hydrogen evolution by adjusting the local pH effect.