Support Interaction Effect of Platinum Nanoparticles on Non-, Y-, Ce-Doped Anatase and Its Implication on the ORR in Acid and Alkaline Media

Platinum nanoparticles (Pt NPs) were prepared by using the photo-assisted method and supported onto oxide-carbon composites synthesized through a modified sol-gel route (M : TiO₂-C, with M=Y and Ce). The physicochemical properties of these materials were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Rietveld refinement was used to identify existing phases of electrocatalysts and to determine the crystallite size. Micro-strain and intrinsic stacking fault increased and decreased, respectively, as a function of crystallite size. Molecular probing via CO-stripping analyses assessed the selectively deposition of Pt NPs onto oxide domains of M : TiO₂-C (M=Y and Ce) supports. This phenomenon can be associated with the formation of the covalent bond at the heterojunction interface between Pt and oxide sites. As confirmed by DFT simulation, this phenomenon was related to the adsorption energy between Pt NPs and Y- or Ce-doped TiO₂. Turnover frequency evaluation revealed that, in acid medium, the strong Pt/oxide interaction promotes the oxygen reduction reaction activity by 1.7-fold, as compared to alkaline medium.