Stabilizing High Metal Loadings of Thermally Stable Platinum Single Atoms on an Industrial Catalyst Support

Single-atom catalysts have attracted attention because of improved atom efficiency, higher reactivity, and better selectivity. A major challenge is to achieve high surface concentrations while preventing these atoms from agglomeration at elevated temperatures. Here we investigate the formation of Pt single atoms on an industrial catalyst support. Using a combination of surface sensitive techniques such as XPS and LEIS, X-ray absorption spectroscopy, electron microscopy, as well as density functional theory, we demonstrate that cerium oxide can support Pt single atoms at high metal loading (3 wt % Pt), without forming any clusters or 3D aggregates when heated in air at 800 degrees C. The mechanism of trapping involves a reaction of the mobile PtO2 with under-coordinated cerium cations present at CeO2(111) step edges, allowing Pt to achieve a stable square planar configuration. The strong interaction of mobile single-atom species with the support, present during catalyst sintering and regeneration, helps explain the sintering resistance of ceria-supported metal catalysts.