Electrochemical CO2 reduction to C2+ products with Cu-oleylamine based nanoparticles synthesized by simple thermal treatment

Cu-based catalysts for CO2 electrochemical reduction reaction suffer from both activity and selectivity towards C2+ products. Here, Cu-Oleylamine (CuOAm) based catalysts with adjustable Cu chemical state are synthesized through thermal reducing method with oleylamine as the only surfactant, solvent, and reducing agent. The catalyst exhibits a high faradaic efficiency of 54% and 79% with a partial current density of 186 mA cm−2 and 245 mA cm−2 at −1.0 V (vs. RHE) for C2H4 and C2+ products, respectively. Further characterizations of the size, morphology and surface composition of CuOAm by XRPD, XPS, SEM, HRTEM, and EDS showed that the presence of different crystal structures (CuO and Cu2O) with comparable amounts were vital for the formation of grain boundary and lattice mismatch during CO2RR. The sequential reduction of CuOx and CO2 at abundant grain boundary and lattice mismatch could facilitate the formation of ethylene and C2+ products, which was confirmed by in-situ Raman measurements under varied potentials.