Urea　(NH2CONH2),　a　crucial　nitrogen　fertilizer　and　industrial　raw　material,　is　typically　synthesized　under　rigorous　reaction　conditions.　Currently,　the　electrocatalytic　transformation　of　N2　and　CO2　into　urea　is　a　promising　strategy.　However,　finding　a　high-selectivity　and　high-activity　catalyst　remains　a　significant　challenge.　Herein,　the　activity　of　a　series　of　transition　metal　clusters　(VIII　and　IB　groups)　on　copper-based　catalysts　for　electrochemical　coupling　of　CO2　and　N2　has　been　systematically　studied　to　produce　urea　via　density　functional　theory　(DFT).　Most　catalysts　exhibit　good　thermodynamic　stability　and　accomplish　co-adsorb　CO2　and　N2.　Notably,　Fe3　and　Ni3/Cu100　catalysts　achieve　C-N　coupling　via　*CO　and　*N2,　whereas　Ru3,　Rh3,　Os3,　and　Ir3/Cu100　catalysts　accomplish　C-N　coupling　via　*CO　and　*NHNH.　Among　all　catalysts,　the　Ni3/Cu100　catalyst　features　excellent　catalytic　activity　with　a　rate-determining　step　as　low　as　0.480　eV,　and　its　C-N　coupling　only　needs　to　overcome　a　barrier　of　0.844　eV.　Additionally,　the　Ni3/Cu100　catalyst　can　effectively　inhibit　the　hydrogen　evolution　reaction　(HER),　further　protonation　of　*CO　and　ammonia　formation,　thereby　ensuring　high　selectivity　for　urea.　Electronic　structures　analysis　further　reveals　an　“acceptance-donation”　mechanism　for　the　activation　of　*CO2　and　*N2,　with　the　introduction　of　the　Ni3　cluster　showing　a　decisive　role.　Therefore,　this　study　may　establish　the　foundation　for　the　electrochemical　synthesis　of　urea.　©　2024　Elsevier　B.V.