Title: Evidence of encapsulation model for strong metal-support interaction under oxidized conditions: A case study on TiOx/Pt(111) for CO oxidation by in situ wide spectral range IRAS

Authors: Huan Li, Xuefei Weng, Zhenyan Tang, Hong Zhang, Ding Ding, Mingshu Chen, and Huilin Wan

Abstract:

Strong metal-support interaction (SMSI) has been found to significantly modify the catalytic performance in the last four decades. The origins of the promotion effects of SMSI still reamin unclear. In this work, fully covered TiOx/Pt(111) model surfaces were prepared to mimic the proposed encapsulation model. The catalytic activities for CO oxidation on such model surfaces as a function of the TiOx coverage were examined in the model catalysis reaction cell. The TiOx ordered thin flims significantly enhanced the reaction rate for CO oxidation on Pt(111). The apparent activation energy was obtained to be 53 kJ/mol for CO oxidation on the TiOx/Pt(111), which is much lower than that of 97 kJ/mol on the clean Pt(111) surface. The stability and catalytic efficiency of such SMSI model surfaces under reaction conditions were confirmed by our home-built in situ wide spectral range infrared reflection adsorption spectroscopy that is capable to measure both the surface species and the changes of a catalyst in one spectrum. The study provides an experimental evidence that a fully covered thin oxide layer can indeed enhance catalytic activities for CO oxidation on Pt catalysts, and confirms the complete encapsulation model. The promotion effects of SMSI may origin from the existing surface sites of the boundary of the two-dimensional thin oxide domains.

Full-Link: https://pubs.acs.org/doi/10.1021/acscatal.8b02883