Photocatalytic hydrogen production over flame spray pyrolysis-synthesised TiO2 and Au/TiO2

A set of titanium dioxide and gold-modified titanium dioxide samples were prepared by flame spray pyrolysis (FP) and characterized by BET, XRD, HRTEM and UV–vis reflectance analysis. Their photocatalytic activity in hydrogen production in water suspension, either from water photosplitting or from methanol photoreforming, was tested in an expressly set up, closed recirculation laboratory scale photoreactor and compared to those of commercial TiO2 samples, including Degussa P25, pure rutile and pure anatase. The rate of hydrogen evolution (rH2rH2) increased with increasing the anatase content, pure anatase being the most active photocatalyst. Surface area and crystallinity, both key properties of photocatalysts, can be tuned up by properly setting FP operation parameters, including the selection of the organic solvent/fuel. In particular, FP-made TiO2 prepared from a xylene solution showed more active than P25. Finally, rH2rH2 increased by one order of magnitude in water photosplitting and by ca. 30 times in methanol photoreforming upon 1% gold addition on TiO2.