Atomically Dispersed Platinum in Surface and Subsurface Sites on MgO Have Contrasting Catalytic Properties for CO Oxidation

Atomically dispersed metals on metal oxide supports are a rapidly growing class of catalysts. Developing an understanding of where and how the metals are bonded to the supports is challenging because support surfaces are heterogeneous, and most reports lack a detailed consideration of these points. Herein, we report two atomically dispersed CO oxidation catalysts having markedly different metal-support interactions: platinum in the first layer of crystalline MgO powder and platinum in the second layer of this support. Structural models have been determined on the basis of data and computations, including those determined by extended X-ray absorption fine structure and X-ray absorption near edge structure spectroscopies, infrared spectroscopy of adsorbed CO, and scanning transmission electron microscopy. The data demonstrate the transformation of surface to subsurface platinum as the temperature of sample calcination increased. Catalyst performance data demonstrate the lower activity but greater stability of the subsurface platinum than of the surface platinum.

Automated summary

Atomically dispersed metals on metal oxide supports are a rapidly growing class of catalysts. Understanding the bonding between metals and supports is challenging due to the heterogeneous nature of support surfaces. This study reports atomically dispersed CO oxidation catalysts with different metal-support interactions and determines their structures using various techniques. The results show the transformation of surface to subsurface platinum with increasing calcination temperature, with the subsurface platinum exhibiting lower activity but greater stability compared to surface platinum.