Pt and Au/TiO2 photocatalysts for methanol reforming: Role of metal nanoparticles in tuning charge trapping properties and photoefficiency

Authors: Alberto Naldoni, Massimiliano D’Arienzo, Marco Altomare, Marcello Marelli, Roberto Scotti, Franca Morazzoni, Elena Selli, Vladimiro Dal Santo

Abstract:
Metal-loaded TiO₂ is, by far, one of the most important class of photocatalysts in hydrogen production through photoreforming of organics and water photosplitting. In this study anatase loaded with Au and Pt nanoparticles (Au/TiO₂ and Pt/TiO₂) by an impregnation-reduction method was investigated as for morphological, electronic (XPS) and photocatalytic properties in hydrogen production by methanol photoreforming. The electron and hole trapping centers, Ti³⁺ and O⁻, respectively, formed under UV–vis irradiation of the photocatalysts, were studied by in situ electron spin resonance (ESR) spectroscopy. The nature ofthe loaded metal affected both the H2 evolution rate and the distribution ofthe methanol oxidation products. The better performance of Pt/TiO₂ is attributable to the greater ability of Pt with respect to Au to act as electron sink, slowering the recombination of photoproduced electron–hole couples. Direct evidence of this effect was obtained by ESR analysis, showing that the amount of Ti³⁺ active sites follows the order TiO₂ >Au/TiO₂ Pt/TiO₂, thus confirming easier electron transfer from Ti³⁺ to Pt, where the H⁺ reduction to H₂ occurs.

Keywords:
Photocatalytic hydrogen production
Titanium dioxide
Gold
Platinum
ESR
Charge trapping centers

Published in: Applied Catalysis B: Environmental (Volumes 130–131, Pages 1-336, 7 February 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

Pt and Au/TiO2 photocatalysts for methanol reforming: Role of metal nanoparticles in tuning charge trapping properties and photoefficiency

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