Differentiating metal-support interactions on Pt/C and Pt/C-TiO₂ electrocatalysts

Carbon-TiO₂ composites were prepared by the solgel method using different TiO₂ contents (0, 3, 5, and 10 % wt.). Platinum nanoparticles (NPs) were photodeposited on carbon and carbon-TiO₂ substrates. The catalysts were characterized by X-ray diffraction (XRD), X-Ray photoelectron spectrometry (XPS), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADFSTEM), and to check the electrocatalytic behavior of the electrodes, the oxygen reduction reaction (ORR) was studied. Photogenerated electrons were used to reduce the platinum cations, and along with a small TiO₂ content, enhance the kinetics of the ORR through an increase of the electron transfer from platinum to the oxygen molecule. However, different phenomena were developed on the surface, depending on the titanium oxide content. The results show the so-called metal-oxide interactions and their effects on electrocatalytic activity.