Electrochemical properties of TiОx–Pt composites

The electrochemical properties of TiOx–Pt electrodes with platinum loadings ranging from 0.3 to 2.0 mg/cm2, both as-deposited (non-heat-treated) and after annealing at 5000C for 3 h, were investigated. Voltammetric measurements were performed in 1 M HClO4. The cyclic voltammograms reveal that the cathodic reduction currents of oxygen-containing platinum species on annealed electrodes are 1.5–2 times lower than those on as-deposited ones, indicating a reduction in the true (active) surface area during heat treatment. The electrocatalytic activity of the prepared materials was evaluated toward the oxygen evolution reaction in 1 M HClO4. Pt-containing electrodes exhibit significantly lower oxygen evolution overpotentials compared to the TiOx electrodes. For as-deposited samples, the oxygen evolution overpotential decreases with increasing a platinum content in the coating. For annealed electrodes, a similar trend is observed. The overpotential for coatings with platinum content of 0.5 mg/cm2 and above remains unchanged. At a Pt loading of 0.3 mg/cm2, the metal layer is not continuous, and the material exhibits a porous structure with platinum islands on TiOx. In contrast, materials with Pt content of 0.5 mg/cm2 and higher maintain porosity, but the metal layer is continuous and uniform.