Titania-Morphology-Dependent Pt–TiO2 Interfacial Catalysis in Water-Gas Shift Reaction

The bifunctional role of the noble-metal–oxide interface in activating reactants is important for efficient heterogeneous catalysis of the water-gas shift (WGS) reaction. Herein, we report that the morphology of the TiO2 support strongly affects the Pt–TiO2 interfacial catalysis for the WGS reaction using Pt nanoparticles of similar sizes supported on anatase TiO2 nanocrystals with various morphologies predominantly exposing {001} facets (denoted TiO2{001}), {100} facets (denoted TiO2{100}), and {101} facets (denoted TiO2{101}). CO conversions follow the order Pt/TiO2{100} ≈ Pt/TiO2{101} > Pt/TiO2{001}, but the apparent activation energies are similar for Pt/TiO2{100}, Pt/TiO2{101}, and Pt/TiO2{001} catalysts. Characterization results show that the Pt/TiO2{001} catalyst exhibits fewer surface oxygen vacancies and consequently active Pt–Ov,TiO2 interfacial ensemble sites than Pt/TiO2{100} and Pt/TiO2{101} catalysts. This can be attributed to the fact that oxygen vacancies are more stable in the bulk of TiO2{001} than on the surface but are more stable on the surface of TiO2{100} and TiO2{101} than in the bulk and to the fact that carbonate and bicarbonate spectators accumulate at the Pt–TiO2 interface at the Pt/TiO2{001} catalyst but barely accumulate the at Pt/TiO2{100} and Pt/TiO2{101} catalysts. Both lead to the poorer catalytic activity of Pt/TiO2{001} catalyst for catalyzing the WGS reaction. These results provide insights into a fundamental understanding of the activity–structure relation of Pt/TiO2 catalysts for the WGS reaction.