Efficient conversion of CO2 to value-added fuels or chemicals using electricity from renewable sources is an appealing approach to realize carbon neutrality. Under this background, it is crucial to design efficient and low-cost catalysts for CO2 electroreduction. Herein, we fabricated an electrocatalyst with the structure of Cu–Ni alloy nanoparticles grown on nitrogen-doped carbon nanotubes (Cu x Ni/NCNT, x = 2.4, 1, and 0.36) for electrochemical CO2 reduction reaction (CO2RR) via a hydrothermal method followed by pyrolysis. The optimized CuNi/NCNT demonstrates a favorable CO2RR performance with a CO Faradaic efficiency (FECO) of 94.8% and a current density of 26.6 mA cm–2 at −0.9 V versus the reversible hydrogen electrode (vs RHE) in the H-cell, far superior to those of single metal counterparts. Density functional theory (DFT) calculations unravel that the Cu–Ni alloys possess much lower free energy changes for the formation of the key COOH* intermediate than those of the Cu metal, thereby facilitating CO2 reduction into CO. Additionally, the CO2RR performance of CuNi/NCNT was further evaluated in the gas diffusion electrode (GDE) involved in the flow cell to examine the practical application of the prepared catalyst, which can deliver a current density of 124.6 mA cm–2 with a FECO of 92.8% at −1.1 V vs RHE. This work enriches electrocatalysts for highly efficient CO2 electroreduction to CO.

The carbon-coated nanoarray structure can be stabilized in alkaline solution, which inhibits the dendrite growth and improves the cell lifetime.