Electronic structure of alumina-supported monometallic Pt and bimetallic PtSn catalysts under hydrogen and carbon monoxide environment.

ABSTRACT

The structure of supported platinum and platinum-tin nanoparticles was investigated by Pt L(3) high-energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD XAS) and resonant inelastic X-ray scattering (RIXS). The incorporation of tin decreased the ability of particles to adsorb both hydrogen and carbon monoxide due to tin enrichment on the surface. The platinum d band of platinum-tin particles was narrower and was shifted down relative to the Fermi level in comparison to platinum particles. The difference in electronic structure between pure and alloyed particles persisted after adsorption of hydrogen. The Pt-H antibonding state was clearly identified for the pure platinum particles. The strong adsorption of carbon monoxide changed the geometric structure of the PtSn particles. After carbon monoxide adsorption, the geometric structures of both systems were very similar. Room temperature adsorption of carbon monoxide affects the structure of platinum catalysts.