Preparation of Cu-La Bimetallic Catalysts by Electrodeposition for the Electrocatalytic Promotion of CO2 to CH4

Methane (CH4) has attracted much attention regarding its use in electrochemical carbon dioxide reduction reaction (CO2RR) due to its high mass-energy density; however, the uneven adsorption of intermediates on copper sites by conventional Cu-based catalysts limits the selective production of CH4. The introduction of a second metal can effectively regulate the adsorption energy of intermediates on the Cu site. In this paper, a method of alloying Cu with oxyphilic metals (M) using rapid electrodeposition is presented; the synergistic effect of the bimetal effectively directed the reaction pathway toward CH4. The best Faraday efficiency for methane occurred in the optimized Cu30La20 electrode, reaching 66.9% at −1.7 V vs. RHE potential. In situ infrared testing revealed that the *CHO intermediate—a critical species for the electrocatalytic conversion of CO2 to CH4—was detected on the Cu30La20 catalytic electrode. However, no *CHO intermediate was observed on the Cu20La30 electrode. Instead, the characteristic peak of the *OCCHO intermediate associated with C-C coupling emerged on the Cu20La30 catalyst. This indicates that the adsorbed oxygen-containing groups on lanthanum sites reacted with carbon-containing groups on copper sites to form C2 products, serving as the primary reason for the shift in reduction products from methane to ethylene.