Production of hydrogen from gas-phase ethanol dehydrogenation over iron-grafted mesoporous Pt/TiO2 photocatalysts

Abstract

We report the photocatalytic activity of iron-grafted mesoporous Pt/TiO₂catalysts, combining the properties of heterojunction photocatalysts with mesoporosity, for the gas-phase production of hydrogen from water-ethanol mixtures. GC–MS analysis reveals a preferential ethanol dehydrogenation reaction pathway, resulting in the formation of acetaldehyde with high selectivity versus carbon dioxide, for all of the catalysts investigated. Multi-technique characterization reveals that, in all the iron-grafted samples, Fe is located predominantly on the surfaces of the catalysts as Fe₂O₃ rather than doping the anatase structure, while the mesoporosity of the starting TiO₂ is preserved. Among the different materials, the activity for photocatalytic ethanol dehydrogenation is optimum in the catalyst with the lowest iron content. According to XPS and time-resolved fluorescence measurements, this can be accounted for by higher Fe surface dispersion and consequent efficient formation of a surface heterojunction between Fe₂O₃ and TiO₂ that favours charge separation.