The effect of Pt characteristics on the photoactivity of Pt/TiO₂ for hydrogen production from ethanol
2013
Navarro, R.M. | Arenales, J. | Vaquero, F. | González, I.D. | Fierro, J.L.G.
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.
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