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.