Stabilization of Cu⁺ sites by amorphous Al₂O₃ to enhance electrochemical CO₂ reduction to C₂₊ products

Catalytic conversion of CO2 to produce fuels and chemicals is of great importance, and the electrocatalytic CO2 reduction reaction (eCO(2)RR) is considered one of the most attractive pathways. Multi-carbon (C2+) products are more desirable in many cases. To date, Cu-based catalysts, especially Cu+ sites, have been found to be the most efficient for the production of C2+ products. However, the retention of Cu+ sites at high cathodic potentials in the eCO(2)RR remains a great challenge. In this study, we designed and synthesized CuAl-oxide-derived (CuxAly-OD, x and y are the mass percentages of Cu and Al) catalysts for the eCO(2)RR to C2+ products. During the eCO(2)RR process, the predominant Cu species changed to Cu+, and the resulting electrocatalyst showed a high faradaic efficiency (FE) of 81.6% for C2+ products in alkaline aqueous solutions. Experimental studies showed that the presence of a stable amorphous Al2O3 phase stabilized the Cu+ sites by oxidation state control, leading to high selectivity and activity for the production of C2+ products. This work provides a strategy for improving the stability of Cu+ in the catalyst to enhance the performance of the eCO(2)RR.