Photosensitization of SiW11O398−-modified TiO2 by Eosin Y for stable visible-light H2 generation

Stability issue of dye limits greatly applications of sensitization systems. In the present work, TiO2 was modified with a lacunary Keggin-type polyoxometalate SiW11O398− (SiW11). SiW11 is bound at TiO2 by a chemical interaction and its modification promotes TiO2 crystallization as well as growth of the particles. The as-prepared SiW11/TiO2 was used to construct a stable and efficient system for visible-light H2 generation using Eosin Y (EY) as a photosensitizer and Pt as a co-catalyst. SiW11 plays a very important role in enhancement of the sensitization activity and stability of SiW11/TiO2. SiW11 as an excellent electron relay greatly facilitates the electron transfer from the reduced dye species EY− to conduction band (CB) of TiO2 and suppresses the decomposition of EY−. Thus, a stable dye-sensitized hydrogen generation system is achieved. The factors which influenced the photocatalytic hydrogen evolution such as concentration of SiW11, concentration of EY, and Pt loading content were investigated. Under the optimal conditions, an average apparent quantum yield of 11.4% was obtained during 20 h irradiation (λ > 420 nm). The possible mechanism was discussed.