Cu–Ni Alloy Nanoparticles Anchored on Nitrogen-Doped Carbon Nanotubes for Efficient CO2 Electroreduction to CO

Efficient conversion of CO 2 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 CO 2 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 CO 2 reduction reaction (CO 2 RR) via a hydrothermal method followed by pyrolysis. The optimized CuNi/NCNT demonstrates a favorable CO 2 RR performance with a CO Faradaic efficiency (FE CO ) 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 CO 2 reduction into CO. Additionally, the CO 2 RR 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 FE CO of 92.8% at −1.1 V vs RHE. This work enriches electrocatalysts for highly efficient CO 2 electroreduction to CO.