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

Selective and stable methane production via electrocatalytic CO2 reduction (eCO2R) 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 CeOχ-Cuδ+ domains to promote bridged adsorption of *CO while pumping up the proton supply through enhanced water dissociation. The high inertia of *CObridge, 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 Ce2%Oχ-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 eCO2R pathway.