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　(similar　to　200　W)　electrolysis　with　ethylene　production　rate　of　16　mL　min-1　.　(c)　2025　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　and　Science　Press.　All　rights　are　reserved,　including　those　for　text　and　data　mining,　AI　training,　and　similar　technologies.