Temperature dependence of the COads oxidation process on Pt(1 1 1), Pt(1 0 0), and Pt(1 1 0) electrodes

Abstract The influence of temperature variation on the CO ads oxidative desorption at Pt(1 1 1), Pt(1 0 0), and Pt(1 1 0) electrodes in 0.5 M H 2 SO 4 and 0.1 M HClO 4 solutions is examined. A distinct shift of the CO ads stripping peak towards less-positive potentials is observed as the temperature is increased from 273 to 333 K. Despite the displacement of the desorption peak towards lower potentials, its current density and shape remain unaffected for the Pt(1 1 1) and Pt(1 0 0) electrodes, therefore indicating that the oxidation mechanism for the CO ads is not influenced by the temperature variation in this particular range. On the other hand, the morphology of the peak on the Pt(1 1 0) electrode changes significantly with the temperature, as a result of the interaction with the oxide formation. The activation energies for the oxidation processes in the two media have been evaluated through the dependence of the peak potential and the voltammetric current of the peak with the temperature. The activation energy obtained in H 2 SO 4 is ca. 15–25 kJ mol −1 higher than that in HClO 4 , highlighting the role of the anions in the oxidation process.