Improving photocatalytic water reduction activity for In2TiO5 by loading metal cocatalysts

In 2 TiO 5 is the only ternary oxide in the In–Ti–O phase diagram. It was prepared by high temperature solid state reaction in this work and verified to be pure with high crystallinity by Le Bail fitting on the powder X-ray diffraction (XRD) pattern. Scanning electron microscopy show that the micrometer particles of In 2 TiO 5 was composed of submicron crystallites. UV–vis diffused reflectance spectra suggested a wide bandgap of 3.55 eV, which is consistent with the theoretical calculations. The bottom of the conduction band is composed of both In 6s and Ti 3d orbitals, however the low density of the states lead to a low density of the charge carriers excited by UV irradiation. Thus the photocatalytic H 2 production rate of In 2 TiO 5 is only 3.6 μmol/h/g in 20 vol% methanol aqueous solution. With the assistance of Ru- and Pt-cocatalyst, the activity is significantly increased and the optimal H 2 evolution rate is 35.7 μmol/h/g when loading 1 wt% Ru and 1 wt% Pt, simultaneously. All the catalysts recovered after the photocatalytic reactions show no degradation according to powder XRD.