Vacuum-Induced Surface Reconstruction of Mn-Ce Oxides for Low-Temperature Coupled Redox Catalysis

Low-temperature redox catalysis over mixed oxides is typically optimized by tuning bulk composition, yet the decisive chemistry occurs at the surface and subsurface interface. Here, we show that this interface can be deliberately reconstructed to enhance Mn-Ce oxide catalysis. Sequential vacuum annealing followed by reduced-pressure O₂ treatment induces near-surface Mn enrichment in an as-prepared Mn-Ce oxide while largely preserving the fluorite CeO₂ framework. This reconstruction increases the near-surface abundance of Mn-containing species, modifies the Mn-Ce-O interfacial electronic and redox environment, and facilitates oxygen activation and redox cycling. Under coupled conditions, R-MnCe achieved 95.5% NO_x conversion at 100°C and complete chlorobenzene conversion at 200°C. In situ spectroscopy and DFT calculations reveal that interfacial electron redistribution lowers the oxygen activation barrier and sustains activated oxygen species that connect NH₃-SCR and chlorobenzene oxidation through a shared oxygen-mediated pathway. These results highlight near-surface reconstruction as a promising postsynthetic strategy for improving noble-metal-free mixed-oxide catalysts.