Selective Hydrogenation on a Highly Active Single-Atom Catalyst of Palladium Dispersed on Ceria Nanorods by Defect Engineering.

Single-atom catalysis represents a new frontier that integrates the merits of homogeneous and heterogeneous catalysis to afford exceptional atom efficiency, activity, and selectivity for a range of catalytic systems. Herein we describe a simple defect engineering strategy to construct an atomically dispersed palladium catalyst (Pdδ+, 0 < δ < 2) by anchoring the palladium atoms on oxygen vacancies created in CeO2 nanorods. This was confirmed by spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurement. The as-prepared catalyst showed exceptional catalytic performance in the hydrogenation of styrene (99% conversion, TOF of 2410 h-1), cinnamaldehyde (99% conversion, 99% selectivity, TOF of 968 h-1), as well as oxidation of triethoxysilane (99% conversion, 79 selectivity, TOF of 10 000 h-1). This single-atom palladium catalyst can be reused at least five times with negligible activity decay. The palladium atoms retained their dispersion on the support at the atomic level after thermal stability testing in Ar at 773 K. Most importantly, this synthetic method can be scaled up while maintaining catalytic performance. We anticipate that this method will expedite access to single-atom catalysts with high activity and excellent resistance to sintering, significantly impacting the performance of this class of catalysts.