The　copper-based　electrocatalysts　feature　attractive　potentials　of　converting　CO2　into　multi-carbon　(C2+)　products,　while　the　instability　of　Cu–O　often　induces　the　reduction　of　Cu+/Cu0　catalytic　sites　at　the　cathode　and　refrains　the　capability　of　stable　electrolysis　especially　at　high　powers.　In　this　work,　we　developed　an　Erbium　(Er)　oxide-modified　Cu　(Er–O–Cu)　catalyst　with　enhanced　covalency　of　Cu–O　and　more　stable　active　sites.　The　f-p-d　coupling　strengthens　the　covalency　of　Cu–O,　and　the　stability　of　Cu+　sites　under　electroreduction　condition　is　critical　for　promoting　the　C–C　coupling　and　improving　the　C2+　product　selectivity.　As　a　result,　the　Er–O–Cu　sites　exhibited　a　high　Faradaic　efficiency　of　C2+　products　(FEC2+)　of　86　%　at　2200　mA　cm−2,　and　a　peak　partial　current　density　of　|jC2+|　of　1900　mA　cm−2,　comparable　to　the　best　reported　values　for　the　CO2-to-C2+　electroreduction.　The　CO2　electrolysis　by　the　Er–O–Cu　sites　was　further　scaled　up　to　100　cm2　to　achieve　high-power　(∼200　W)　electrolysis　with　ethylene　production　rate　of　16　mL　min−1.　©　2025　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences