Enhancement of Photocatalytic Activity for Hydrogen Production by Surface Modification of Pt‐TiO<sub>2</sub> Nanoparticles with a Double Layer of Photosensitizers
Nobutaka Yoshimura, Atsushi Kobayashi, Masaki Yoshida, Masako Kato
Abstract
Abstract To investigate the effect of the surface structure of dye‐sensitized photocatalyst nanoparticles, we prepared three types of Ru II ‐photosensitizer (PS)‐double‐layered Pt‐cocatalyst‐loaded TiO 2 nanoparticles with different surface structures, Zr‐ RuCP 6 ‐Zr‐ RuP 6 @ N wt %Pt‐TiO 2 , RuCP 6 ‐Zr‐ RuP 6 @ N wt %Pt‐TiO 2 , and RuCP 2 ‐Zr‐ RuP 6 @ N wt %Pt‐TiO 2 ( N =0.2, 1, and 5), and evaluated their photocatalytic H 2 evolution activity in the presence of redox‐reversible iodide as the electron donor. Although the driving force of the electron injection from I − to the photo‐oxidized Ru III PS is comparable, the activity increased in the following order: RuCP 2 ‐Zr‐ RuP 6 @1 wt %Pt‐TiO 2 < RuCP 6 ‐Zr‐ RuP 6 @1 wt %Pt‐TiO 2 < Zr‐ RuCP 6 ‐Zr‐ RuP 6 @1 wt %Pt‐TiO 2 . The apparent quantum yield of Zr‐ RuCP 6 ‐Zr‐ RuP 6 @1 wt %Pt‐TiO 2 in the first hour reached 1 %. Zeta‐potential measurements suggest that the surface Zr 4+ ‐phosphate groups attracted I − anions to the nanoparticle–solution interface. Our results indicate that the surface modification of dye‐sensitized photocatalysts is a promising approach to enhance photocatalytic activity with various redox mediators.