Disclosure of the Surface Composition of TiO2-Supported Gold Palladium Bimetallic Catalysts by High-Sensitivity Low-Energy Ion Scattering Spectroscopy

摘要

It is well-known that there is a critical relationship between the surface composition and activity for a bimetallic catalyst. However, the surface is normally reconstructed under different conditions, which makes the surface more complicated. In this work, TiO2-supported colloidal PdxAuy-NPs with different atomic ratios were prepared and treated under oxidation, reduction, and actual catalytic reaction conditions. The surface composition and structure were measured using X-ray photoelectron spectroscopy (XPS) and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS). Phase diagrams of the surface compositions composition were established. Oxidation induces dealloying and enrichment of PdO on the surface, while H-2 reduction results in realloying with just slight surface enrichment of Pd. Gold helps Pd to resist oxidation and enhances its activity for CO oxidation at low temperature. under various conditions function of the bulk