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

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. TiOx overlayers appeared on the surface of large Pt particles (10–12 nm) that were observed only occasionally in the samples.