CuSn Alloy Nanoparticles on Nitrogen-Doped Graphene for Electrocatalytic CO₂ Reduction

We report an efficient electrocatalyst utilizing non-noble metals consisting of Cu and Sn supported on nitrogen-doped graphene (NG) for reduction of CO₂ over a wide potential range. The CuSn alloy nanoparticles (NPs) on NG were prepared through a hydrothermal method followed by pyrolysis under nitrogen atmosphere to achieve a uniform dispersion of the alloy NPs. The CuSn NP (Cu/Sn ratio of 0.175) decorated NG catalyst performed electrocatalytic reduction of CO₂ into C1 products at a Faradaic efficiency (FE) of nearly 93 % at an overpotential of -1.0 V vs. RHE, considerably higher than that of the Cu and Sn counterparts, i. e., 32 % and 58 %, respectively. The enhanced catalytic activity could be attributed to the collaboration between the CuSn alloy and Sn metal. The first-principles density functional theory (DFT) simulation results indicate that the CuSn bimetal alloy nanoparticles enable more H atoms to participate in the electrocatalytic reduction of CO₂ and exhibit an improved CO₂ capture performance. In addition, the CuSn alloy having a lower barrier than that of Sn metal can accelerate the CO₂ reduction process. This study presents the strategy that utilizes low-cost non-noble metals as highly efficient electrocatalysts for aqueous reduction of CO2.