Abstract Critical influence of local active-site concentration and configuration on CO 2 reduction selectivity remains rarely explored, due to the challenge in constructing well-defined structures. In this study, we employ a molten salt-assisted strategy to synthesize Ce-O V -Cu cascade catalyst with tunable configurations and relative concentrations of Cu and Ce-O V sites. Two distinct geometries were constructed: one featuring dense Cu sites surrounding Ce-O V , and another with isolated Cu centers encapsulated by Ce-O V . These configurations effectively direct the key *CHO or *COH intermediates toward either coupling with *CO or hydrogenation with *H, thereby switching product selectivity. The CuCe 10 O x catalyst with isolated copper centers achieves a high CH 4 Faradaic efficiency (FE) of 61.7% at −1.6 V vs. reversible hydrogen electrode (RHE), whereas the local Cu-rich Cu 10 CeO x variant favors C 2 production with a maximum FE of 61.5% at −1.4 V vs. RHE. Mechanistic studies reveal that locally concentrated Cu sites exhibit strong *CO 2 binding affinity, enhancing *CO surface coverage and facilitating *CO–*COH coupling; while Ce-O V -rich regions with isolated copper center supply abundant availability *H, promoting deep protonation of *CHO intermediate toward CH 4 . This work offers valuable insights into catalyst design, where manipulating structural chemistry guides catalytic processes toward targeted CO 2 RR products.
Zhu et al. (2026) studied this question.