We report the photocatalytic activity of iron-grafted mesoporous Pt/TiO2 catalysts, 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. Multitechnique 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.

This work has received financial support from Spanish MCIN/AEI/ 10.13039/501100011033 and "ERDF A way of making Europe", through projects PID2020-118593RB-C22 and ENE2017-89170-R, from Comunidad de Madrid and European Structural Funds through FotoArt-CM project (S2018/NMT-4367).The work at UCSB was supported by the Institute for Collaborative Biotechnologies through Grant No. W911NF-09-0001 from the U. S. ARO.