Unlocking the potential of CuNi bimetallic catalyst: Structural innovation in phase-separated design for efficient electrochemical CO2 reduction

Bimetallic catalysts are widely used in electrochemical CO 2 reduction reactions (ECRR). However, the study of structural effects of bimetallic catalysts on ECRR is still limited. Herein, two kinds of nitrogen-doped carbon-supported CuNi bimetallic catalysts with alloy structure (CuNi/NC-alloy) and phase-separated structure (CuNi/NC-PS) were prepared, respectively, and their ECRR performance were studied. Interestingly, compared with CuNi/NC-alloy, the unique phase separation structure in the CuNi/NC-PS catalyst made the d-band center of Ni the most moderate, balancing the bonding strength with *COOH and *CO, making it not only exhibited relatively low CO 2 activation barrier but also not been poisoned by CO, thus exhibiting higher CO selectivity. Therefore, CuNi/NC-PS exhibited superior catalytic activity (−0.86 V vs. RHE, FE CO = 94.03 %, j CO = 37.06 mA cm −2 ) compared to CuNi/NC-alloy. In the membrane electrode assembly, based on CuNi/NC-PS catalyst and Co/Mo metal–organic frameworks (Co/Mo-MOF) catalyst, the coupling of formaldehyde oxidation and CO 2 reduction could save 22 % energy consumption at the current density of 100 mA cm −2 and obtain high value-added anode product HCOO − . This study will lay a foundation for understanding the structural effects of CuNi based bimetallic catalysts on their electrocatalytic activities.