Performance Enhancement and Active Sites Identification of Cu-Cd Bimetallic Oxide Derived Catalysts for Electrochemical CO2 Reduction

The development of earth-abundant electrocatalysts with high performance for electrochemical CO2 reduction (ECR) is of great significance. Cu-based catalysts have been widely investigated for ECR due to their unique ability to generate various carbonaceous products, but directing selectivity toward one certain product and identifying the real active sites during ECR are still full of challenge. Here, after the incorporation of CdO into CuO, the Cu0.5Cd0.5-O catalyst achieves a 10.3-fold enhancement for CO selectivity in comparison with CuO, and a CO faradic efficiency nearly 90% with a current density around 20 mA cm−2 could maintain at least 60 h. Interestingly, a wide CO/H2 ratio (0.07–10) is reached on CuxCd1−x-O catalysts by varying the Cu/Cd ratio, demonstrating the potential of syngas production using such catalysts. The results of ex situ XRD, XPS, and in situ Raman reveal that the real active sites of Cu0.5Cd0.5-O catalysts for CO production during ECR reaction are the reconstructed mixed phases of CuCd alloy and CdCO3. In situ FTIR and theoretical calculations further implicate the presence of Cd related species promotes the CO desorption and inhibits the H2 evolution, thus leading to an enhanced CO generation.