Hydrogen production over metal-loaded mesoporous-assembled SrTiO3 nanocrystal photocatalysts: Effects of metal type and loading

Mesoporous-assembled SrTiO3 photocatalysts with different loaded metal co-catalysts (Au,Pt, Ag, Ni, Ce, and Fe) synthesized by the single-step sol–gel method with the aid of a structure-directing surfactant were tested for the photocatalytic activity of hydrogen production from a methanol aqueous solution under both UV and visible light irradiation. The Au, Pt, Ag, and Ni loadings had a positive effect on the photocatalytic activity enhancement, whereas the Ce and Fe loadings did not. The best loaded metal was found to be Au due to its electrochemical properties compatible with the SrTiO3-based photocatalyst and its visible light harvesting enhancement. A 1 wt.% Au-loaded SrTiO3 photocatalyst exhibited the highest photocatalytic hydrogen production activity with a hydrogen production rate of 337 and 200 μmol h−1 gcat−1 under UV and visible light irradiation, respectively. The hydrogen diffusivity from the liquid phase to the gas phase also significantly affected the photocatalytic hydrogen production efficiency. An increase in the hydrogen diffusability led to an increase in the photocatalytic hydrogen production efficiency.