Metal–Support Interaction in Pt/TiO2: Formation of Surface Pt–Ti Alloy

• Published in: Journal of physical chemistry. C Vol. 125; no. 19; pp. 10386 - 10396
• Main Authors: Zhao, Wenning, Zhou, Di, Han, Shaobo, Li, Yong, Liu, Jiaxu, Zhou, Yan, Li, Mingrun, Zhang, Xixiong, Shen, Wenjie
• Format: Journal Article
• Language: English
• Published: American Chemical Society 20.05.2021
• Subjects: adsorption; air; alloys; C: Chemical and Catalytic Reactivity at Interfaces; hydrogen; nanosheets; spectroscopy
• ISSN: 1932-7447; 1932-7455; 1932-7455
• DOI: 10.1021/acs.jpcc.1c02108

Pt/TiO2 catalysts were fabricated by dispersing uniform Pt colloids of 3.0 nm on TiO2 nanosheets that preferentially exposed the {001} facets; the chemical nature of the metal–support interaction was examined by hydrogen treatment at 473–773 K. Upon calcination of the freshly assembled sample at 773 K in air, for removing the organic species, Pt particles retained a mean size of about 3.0 nm, but were partially split into tiny clusters and even single-atoms. The subsequent reduction with hydrogen at 473–773 K lowered the amounts of the chemically adsorbed H2 and CO, showing the prominent character of a strong metal–support interaction. However, detailed spectroscopic and microscopic characterizations on the structural evolution of the H2-reduced samples evidenced that surface Pt–Ti alloy, formed over the Pt particle, dominated the metal–support interaction. Driven by the small size of the Pt particle and the reactive {001} facets of TiO2, surface Pt–Ti alloy was readily formed at 673 K under H2, which heavily weakened the adsorption of the probe molecules. TiO x overlayers appeared on the surface of large Pt particles (10–12 nm) that were observed only occasionally in the samples.