Selective adsorption of trace H_2O over O_2 on Pt/Fe/Pt(111) surface of Pt-Fe catalyst

摘要

The selective adsorption of trace water over O-2 is reported on Pt/Fe/Pt(1 1 1) surface of Pt-Fe model catalysts by using high resolution electron energy loss spectroscopy (HREELS) The Pt/Fe/Pt(1 1 1) surface has a sandwich structure of the topmost Pt atomic layer, subsurface Fe layer and underlying Pt(1 1 1) bulk, and presents the lower density of states (DOS) at 0-2.0 eV below the Fermi level with reference to Pt(1 1 1). On the Pt/Fe/Pt (1 1 1) surface the chemisorption of both O-2 and H2O would be weakened with different extents, which would change the relative order of their adsorption strength. At 105 K and exposure to O-2 with 0.1% v/v water, chemisorbed water species are dominated on the Pt/Fe/Pt(1 1 1) surface, while chemisorbed O-2 species are dominated on Pt(1 1 1) surface. The selective adsorption of trace water on Pt/Fe/Pt(1 1 1) surface could provide a hint that the well-tuned electronic structure of bimetallic catalysts might change the relative amount of surface species significantly and produce an influential effect on the CO reaction route at low temperatures.