Controlled assembly of Cu nanoparticles on pyridinic-N rich graphene for electrochemical reduction of CO₂ to ethylene

Monodisperse Cu nanoparticles (NPs) assembled on a pyridinic-N rich graphene (p-NG) support show a Cu NP mass- and size-dependent catalysis for the selective electrochemical reduction of CO₂ to ethylene (C₂H₄). For the 7 nm Cu NPs assembled on the p-NG with the p-NG/Cu mass ratio of 1:1, the C₂H₄ formation Faradaic efficiency and hydrocarbon selectivity reach 19% and 79% respectively at -0.9 V (vs reversible hydrogen electrode). The p-NG itself can catalyze the CO₂ reduction to formate, but in the composite p-NG-Cu structure, the pyridinic-N functions as a CO₂ and proton absorber, facilitating hydrogenation and carbon-carbon coupling reactions on Cu for the formation of C₂H₄. The work demonstrates a new strategy to improve Cu NP catalytic activity and selectivity for the electrochemical reduction of CO₂ for sustainable chemistry and energy applications.