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} approximate to 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.

Automated summary

The morphology of the TiO2 support strongly influences the interfacial catalysis of Pt-TiO2 for the water-gas shift (WGS) reaction. Pt/TiO2{001} catalyst exhibits fewer surface oxygen vacancies and consequently active Pt-Ov,TiO2 interfacial ensemble sites compared to Pt/TiO2{100} and Pt/TiO2{101} catalysts, resulting in lower catalytic activity.