Significance of Epitaxial Growth of PtO 2 on Rutile TiO 2 for Pt/TiO 2 Catalysts.

TiO 2 -supported Pt species have been widely applied in numerous critical reactions involving photo-, thermo-, and electrochemical-catalysis for decades. Manipulation of the state of the Pt species in Pt/TiO 2 catalysts is crucial for fine-tuning their catalytic performance. Here, we report an interesting discovery showing the epitaxial growth of PtO 2 atomic layers on rutile TiO 2 , potentially allowing control of the states of active Pt species in Pt/TiO 2 catalysts. The presence of PtO 2 atomic layers could modulate the geometric configuration and electronic state of the Pt species under reduction conditions, resulting in a spread of the particle shape and obtaining a Pt/PtO 2 /TiO 2 structure with more positive valence of Pt species. As a result, such a catalyst exhibits exceptional electrocatalytic activity and stability toward hydrogen evolution reaction, while also promoting the thermocatalytic CO oxidation, surpassing the performance of the Pt/TiO 2 catalyst with no epitaxial structure. This novel epitaxial growth of the PtO 2 structure on rutile TiO 2 in Pt/TiO 2 catalysts shows its potential in the rational design of highly active and economical catalysts toward diverse catalytic reactions.