Tracking structural evolution: operando regenerative CeO(x)/Bi interface structure for high-performance CO(2) electroreduction

Unveiling the structural evolution and working mechanism of catalysts under realistic operating conditions is crucial for the design of efficient electrocatalysts for CO(2) electroreduction, yet remains highly challenging. Here, by virtue of operando structural measurements at multiscale levels, it is identified under CO(2) electroreduction conditions that an as-prepared CeO(2)/BiOCl precatalyst gradually evolves into CeO(x)/Bi interface structure with enriched Ce(3+) species, which serves as the real catalytically active phase. The derived CeO(x)/Bi interface structure compared to pure Bi counterpart delivers substantially enhanced performance with a formate Faradaic efficiency approaching 90% for 24 hours in a wide potential window. The formate Faradaic efficiency can be further increased by using isotope D(2)O instead of H(2)O. Density functional theory calculations suggest that the regenerative CeO(x)/Bi interfacial sites can not only promote water activation to increase local (*)H species for CO(2) protonation appropriately, but also stabilize the key intermediate (*)OCHO in formate pathway.