Photoinduced Deposition of Platinum from (Bu 4 N) 2 [Pt(NO 3 ) 6 ] for a Low Pt-Loading Pt/TiO 2 Hydrogen Photogeneration Catalyst.

An efficient method for the deposition of ionic platinum species PtO _x onto a TiO ₂ surface was developed on the basis of light-induced activation of the [Pt(NO ₃ ) ₆ ] ^2- anion. The deposited PtO _x species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtO _n } and polyatomic ensembles {Pt _n O _m } connected to a TiO ₂ surface with Pt-O-Ti bonds. The resulting PtO _x /TiO ₂ 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 H ₂ 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 PtO _x species leads to the formation of well-dispersed nanoparticles of metallic platinum attached on the surface of TiO ₂ by Ti-O-Pt bonds. The high activity of the PtO _x /TiO ₂ materials is believed to result from a combination of uniform distribution of small platinum nanoparticles over the titania surface and their close interaction with TiO ₂ .