Revealing the structure-activity relationship of Pt₁/CeO₂ with ¹⁷O solid-state NMR spectroscopy and DFT calculations

Single-atom catalysts (SACs) have attracted significant interest due to their exceptional and tunable performance, enabled by diverse coordination environments achieved through innovative synthetic strategies. However, various local structures of active sites pose significant challenges for precise characterization, a prerequisite for developing structure-activity relationships. Here, we combine ¹⁷O solid-state NMR spectroscopy and DFT calculations to elucidate the detailed structural information of Pt/CeO₂ SACs and their catalytic behaviors. The NMR data reveal that single Pt atoms, dispersed from clusters with water vapor, exhibit a square planar geometry embedded in CeO₂ (111) surface, distinct from the original clusters and other conventionally generated Pt single atoms. The square planar Pt/CeO₂ SAC demonstrates improved CO oxidation performance compared to Pt/CeO₂ SAC with octahedral coordination, due to moderately strong CO adsorption and low energy barriers. This approach can be extended to other oxide-supported SACs, enabling spatially resolved characterization and offering comprehensive insights into their structure-activity relationships.