Temperature Dependence of CO Chemisorption and Its Oxidative Desorption on the Pt(111) Electrode

The influence of temperature variation on the COchem oxidative desorption on Pt(111) electrodes is examined. A distinct shift of the COchem 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 T ≤ 318 K), therefore indicating that the oxidation mechanism for the COchem is not influenced by the temperature variation in this particular range. On the other hand, the coverage of the COchem overlayer is clearly influenced by the temperature change. At T ≤ 318 K, the COchem coverage is 0.68 while at T > 318 K there is a sharp decrease in the COchem coverage to 0.54. The linear dependence of the peak potential with the temperature allows us to determine the apparent activation energy of the process which is found to be 132 ± 3 kJ mol-1. This value agrees well with the literature value that proposes that process proceeds with formation of (Pt−CO···OH−Pt)⧧ as the activated complex.