Photoinduced Deposition of Platinum from (Bu₄N)₂[Pt(NO₃)₆] for a Low Pt-Loading Pt/TiO₂ Hydrogen Photogeneration Catalyst

An efficient method for the deposition of ionic platinum species PtOx onto a TiO2 surface was developed on the basis of light-induced activation of the [Pt(NO3)6]2- anion. The deposited PtOx species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtOn} and polyatomic ensembles {PtnOm} connected to a TiO2 surface with Pt-O-Ti bonds. The resulting PtOx/TiO2 materials were tested as photocatalysts for the hydrogen evolution reaction (HER) from a water ethanol mixture and have shown uniquely high activity with the rate of H2 evolution achieving 11 mol h-1 per gram of Pt, which is the highest result for such materials reported to date. A combination of spectral methods shows that, under HER conditions, reduction of the supported PtOx species leads to the formation of well-dispersed nanoparticles of metallic platinum attached on the surface of TiO2 by Ti-O-Pt bonds. The high activity of the PtOx/TiO2 materials is believed to result from a combination of uniform distribution of small platinum nanoparticles over the titania surface and their close interaction with TiO2.