Pushing the Performance Limit of Cu/CeO Catalyst in CO Electroreduction: A Cluster Model Study for Loading Single Atoms.

Pushing the performance limit of catalysts is a major goal of CO electroreduction toward practical application. A single-atom catalyst is recognized as a solution for achieving this goal, which is, however, a double-edged sword considering the limited loading amount and stability of single-atom sites. To overcome the limit, the loading of single atoms on supports should be well addressed, requiring a suitable model system. Herein, we report the model system of an ultrasmall CeO cluster (2.4 nm) with an atomic precise structure and a high surface-to-volume ratio for loading Cu single atoms. The combination of multiple characterizations and theoretical calculations reveals the loading location and limit of Cu single atoms on CeO clusters, determining an optimal configuration for CO electroreduction. The optimal catalyst achieves a maximum Faradaic efficiency (FE) of 67% and a maximum partial current density of -364 mA/cm for CH, and can maintain high CH FE values over 50% in a wide range of applied current densities (-50 ∼ -600 mA/cm), exceeding those of the reported catalysts.