Carbon-TiO2 composites were prepared by the sol-gel method using different TiO2 contents (0, 3, 5, and 10 % wt.). Platinum nanoparticles (NPs) were photo-deposited 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 (HAADF-STEM), 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.
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