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 (eCO₂RR) 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 eCO₂RR remains a great challenge. In this study, we designed and synthesized CuAl-oxide-derived (Cu_xAl_y-OD, x and y are the mass percentages of Cu and Al) catalysts for the eCO₂RR to C₂₊ products. During the eCO₂RR 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 eCO₂RR.