Sorption-determined deposition of platinum on well-defined platelike WO3.

The photodeposition of Pt nanoparticles from [PtCl6 ](2-) on platelike WO3 crystals occurs preferentially on the small, subordinate facets. Rather than the often-used explanation of preferred light-induced charge migration, we propose that this phenomenon is due to differences in the intrinsic surface charges of WO3 facets exposed to water; thus, the dark sorption of [PtCl6 ](2-) on positively charged facets/edges is preferred. This conclusion is based on 1) (dark) impregnation studies, which showed Pt deposition to also be facet-specific, and 2) aqueous-phase AFM studies, which suggest intrinsic surface charges to be in agreement with sorption-based Pt distributions.