The effect of Pt characteristics on the photoactivity of Pt/TiO2 for hydrogen production from ethanol

Pt/TiO2 photo-catalysts prepared by different methodologies (deposition–precipitation and wet impregnation using various Pt precursors) are investigated for the photo-production of hydrogen from aqueous solutions of ethanol. Textural, structural and surface catalyst properties are determined by N2 adsorption isotherms, UV–vis spectroscopy, XRD and XPS and related to the photo-activity results. Physicochemical characterization of Pt/TiO2 samples revealed differences in the electronic state and surface concentration of Pt nanoparticles depending on the method of preparation. Stronger interaction of Pt nanoparticles with TiO2 support that leads to some partially charged Pt particles was observed in the samples prepared by the deposition–precipitation (Ptδ−) and by impregnation (Ptδ+) using neutral Pt acetylacetonate precursor. It is found that H2 production rates on Pt/TiO2 photo-catalysts depend on the characteristics of Pt particles showing the partially charged Pt particles (Ptδ−and Ptδ+) better intrinsic photoactivity than that observed for metallic Pt counterpart. The improvement in the intrinsic activity observed for the partially charged Pt particles is attributed to a better e-conductivity (in the case of Ptδ− particles) and an increase in the adsorption of surface molecules (in the case of Ptδ+) extending the e-/hole carrier separation of TiO2 photo-catalyst.