Atomistic and Oxophilic Ce Raises the Inertia of CO Intermediates Toward Enhanced Electrocatalytic Methanation

Abstract Selective and stable methane production via electrocatalytic CO 2 reduction (eCO 2 R) utilizing membrane electrode assembly (MEA) has been challenging, requiring a delicate balance of surface coverage and binding energy among intermediates such as * CO and * H. This study addresses these challenges by doping oxophilic cerium (Ce) into a copper (Cu) matrix through thermal co‐evaporation, creating atomistic CeO χ ‐Cu δ+ domains to promote bridged adsorption of * CO while pumping up the proton supply through enhanced water dissociation. The high inertia of * CO bridge , as co‐stabilized by * OH, and the high proton availability, effectively inhibit C─C coupling while prompting intermediates hydrogenation, ultimately leading to improved methane production. The optimized Ce 2% O χ ‐Cu catalyst achieves an unprecedented stability in MEA operation for over 210 h with an average methane selectivity above 50%. This work offers profound understanding on synergistically tuning intermediates binding and water dissociation through oxophilic rare‐earth doping to steer the eCO 2 R pathway.