Single-Atom Rh on High-Index CeO₂ Facet for Highly Enhanced Catalytic CO Oxidation

Reducible oxide-supported noble metal nanoparticles exhibit high activity in catalyzing many important oxidation reactions. However, atom migration under harsh reaction conditions leads to deactivation of the catalyst. Meanwhile, single-atom catalysts demonstrate enhanced stability, but often suffer from poor catalytic activity owing to the ionized surface states. In this work, we simultaneously address the poor activity and stability issues by synthesizing highly active and durable rhodium (Rh) single-atom catalysts through a "wrap-bake-peel" process. The pre-coated SiO₂ layer during synthesis of catalyst plays a crucial role in not only protecting CeO₂ support against sintering, but also donating electron to weaken the Ce-O bond, producing highly loaded Rh single atoms on the CeO₂ support exposed with high-index {210} facets. Benefiting from the unique electronic structure of CeO₂ {210} facets, more oxygen vacancies are generated along with the deposition of more electropositive Rh single atoms, leading to remarkably improved catalytic performance in CO oxidation.