Title: Disclose the surface composition of TiO2 supported gold-palladium bimetallic catalysts by high-sensitivity low energy ion scattering spectroscopy

Authors: Yangyang Li, Jun Hu, Dongdong Ma, Yanping Zheng, Mingshu Chen, and Huilin Wan

Abstract:

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 under various conditions as a function of the bulk composition were established. Oxidation induces de-alloying and enrichment of PdO on the surface, while H2 reduction results in re-alloying with just slight surface enrichment of Pd. Gold can help Pd against oxidation, and enhances its activity for CO oxidation at low temperature.

Full-Link: http://pubs.acs.org/doi/10.1021/acscatal.7b03839