Enhanced Heterogeneous Hydroformylation of 1-Hexene on Rh ₁ /CeO ₂ Single-Atom Catalysts: Preinduced Oxygen Vacancies

Heterogeneous hydroformylation reduces the use of phosphine ligands and allows catalyst recycling. Although the interaction between single atoms and supports significantly affects the catalytic activity and stability, the structure–performance relationship in hydroformylation systems remains unclear. Herein, Rh 1 /CeO 2 single-atom catalysts with different oxygen vacancy concentrations were prepared on commercially available supports. Higher reduction temperatures introduced more oxygen vacancies adjacent to Rh single-atom sites, improving the catalytic activity by 63%. However, excessively high temperatures caused Rh aggregation, and the resulting clusters were detrimental to activity. Under optimal conditions, Rh 1 /CeO 2 -600 showed the highest hydroformylation activity, with a turnover frequency of 7761 h –1 . The density functional theory calculations further demonstrated that adjacent oxygen vacancies alter the rate-determining step and thus decrease the overall activation energy. This work illustrates the molecular mechanism of the structure–performance relationship regarding oxygen vacancies and provides guidance for rational design of subsequent heterogeneous catalysts.