XAFS study on a photodeposition process of Pt nanoparticles on TiO₂ photocatalyst

A photodeposition process of Pt metal particles on anatase TiO₂ in the aqueous solution of H₂PtCl₆ (precursor) and methanol (reductant) was studied using transmission electron microscopy, UV-vis spectroscopy and X-ray absorption fine structure spectroscopy. These analyses proposed the photodeposition mechanism of Pt on TiO₂ by the photogenerated electrons: the photo-assisted adsorption of Pt⁴⁺ complexes on TiO₂ through the ligand exchange at the initial stage, followed by the successive rapid reduction of Pt⁴⁺ to Pt⁰ to grow the Pt metal particles, which gives small and almost uniform size of Pt metal nanoparticles. (paper)