Oxidatibn of Oxygen-Containing C₁ Compounds of Platinum Electrode

Abstract

Methanol is a likely alternative to petroleum-derived fuels and a number of electrochemical investigation have been reported on Pt electrode. However, results, appear rather scattered, depending highly on experimental conditions. The aims of the present paper are to understand general features of the electrooxidation of the 0-containirig C₁ compounds such as CO, HCOOH and CH₃OH on the identical experimental conditions.
The experiments were carried out by the usual electrochemical method but the special attention was paid to standardization of the surface state of the Pt electrode, the concentration of the reactants and the experimental procedures.
The steady state polarization measure ments show that the CH3OH oxidation, is slower by 1 to 2 orders of magnitude than those of HCOOH (acid) and CO. HC00^- does not oxidize in alkaline solution. The competitive oxidation of the reactants indicates that the slow CH₃OH oxidation is due to the weak interaction of CH₃OH with the Pt surface. The weak interaction can be explained by a high geometrical requirement for the adsorption sites but not by any special, poisoning effects of the adsorbed species since the latter is found to be a common species and present to an almost equal amount at the CH₃OH, HCOOH(Na), CO oxidations.
The surface oxida tion process of CH₃OH and HCOOH(Na) and CO will proceed by a common mechanism since their voltammograms undergo a sharp and drastic change in a common way at a solution pH of about 11. The CH₃OH oxidation mechanism was further discussed in detail.