Highly Active and Stable Cu-Cd Bimetallic Oxides for Enhanced Electrochemical CO₂ Reduction

Electrochemical reduction of carbon dioxide (CO₂) can produce value-added chemicals such as carbon monoxide (CO) and multicarbon (C₂₊). However, the complex reaction pathways of CO₂ electro-reduction reaction (CO₂RR) greatly limit the product selectivity and conversion efficiency. Herein, the Cu-Cd bimetallic oxides catalyst was designed and applied for the CO₂RR. The optimized 4.73 %Cd-CuO exhibits remarkable electrocatalytic CO₂RR activity for selective CO production in H-cell using 0.5 M 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF₆)/MeCN as electrolyte. The Faradaic efficiency of CO (FE(CO)) can be maintained above 90 % over a wide potential range of -2.0 to -2.4 V vs. Ag/Ag⁺. Particularly, the catalyst achieves an impressive FE(CO) of 96.3 % with a current density of 60.7 mA cm^-2 at -2.2 V vs. Ag/Ag⁺. Furthermore, scaling up the 4.73 %Cd-CuO catalyst into a flow cell can reach 56.64 % FE of C₂₊ products (ethylene, ethanol and n-propanol) with a current density as high as 600 mA cm^-2 steadily. The excellent CO₂RR performance of the as-synthesized 4.73 %Cd-CuO can be mainly attributed to the introduction of CdO to improve the ability of CuO to activate CO₂, the electronic interactions between Cu and Cd can boost the activation and conversion the key intermediates of CO₂RR and ensure the continuous stability of the 4.73 %Cd-CuO in electrolysis process.