Facet-Dependent Activity of Pt Nanoparticles as Cocatalyst on TiO2Photocatalyst for Dye-Sensitized Visible-Light Hydrogen Generation

The photocatalytic activities of polyoriented and preferential Pt(111) nanoparticles supported on TiO2(Pt(poly)/TiO2and Pt(111)/TiO2) were investigated by the photocatalytic hydrogen generation from water under visible-light irradiation. The photocatalytic hydrogen production rate of Pt(111)/TiO2was 1.6 times higher than that of Pt(poly)/TiO2. The corresponding apparent activation energy on Pt(111)/TiO2was about 2.39 KJ/mol, while on Pt(poly)/TiO2, it was about 4.83 KJ/mol. The difference in the apparent activation energies was probably due to the diversity in the number of surface atoms at corners and edges between the Pt(poly) and Pt(111) nanoparticles. The photocurrent of Pt(111)/TiO2was also bigger than that of Pt(poly)/TiO2, implying that the surface structure of Pt(111) nanoparticles can improve the transfer efficiency of photo-induced electrons from the conduction band of TiO2to Pt nanoparticles. As a result, the surface structure of Pt nanoparticles played an important role in the reactivity and kinetics performance of hydrogen evolution. Therefore, the photocatalytic properties of Pt/TiO2strongly depended on the surface structure of Pt nanoparticles.