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

Abstract

Bimetallic catalysts are widely used in electrochemical CO2 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 CO2 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, FECO = 94.03 %, jCO = 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 CO2 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.