Trace Ni2+-Assisted Crystallization Regulation of Cu-Based Electrocatalysts for Enhanced Methane Production in CO2 Reduction

Electrocatalytic CO 2 reduction reaction (CO 2 RR) stands as a pivotal strategy for the selective conversion of CO 2 into high-energy-density hydrocarbons, offering a promising avenue for carbon neutrality. Cu-based electrodes have emerged as a highly potential platform for the production of diverse products, yet their practical application is hindered by the crystallization regulation of electrocatalysts achieving high selectivity for multielectron products. Here, we report Cu-based electrodes, deposited on carbon paper via facile one-step coelectrodeposition methods, for efficient electrocatalytic CO 2 RR. The introduction of trace Ni was found to smooth the surface of Cu-based electrocatalysts, thereby facilitating the electron transfer at the catalytic interface. For CuNi 0.3% electrode, a maximum Faraday efficiency of 30.5% and a CH 4 yield rate of 16.4 mg h −1 cm −1 were achieved at −1.4 V versus RHE, outperforming the Cu electrode (17.9% FE) and the CuNi 0.6% electrode (26.9%). This enhancement might be attributed to the superior surface of the CuNi 0.3% electrocatalyst, with the trace amount of Ni 2+ codeposition playing a critical role in optimizing the smooth surface of the Cu electrode. Density functional theory calculations further revealed that Ni addition is thermodynamically favorable for the deep hydrogenation of *CO by lowering the formation energies of *CO and *COH intermediates.