Abstraet---4)n the anodic fast-potential-sweep curve made on platinized platinum in acid solutions containing CH,OH and HCOOH an "adsorption" peak appears, the potential of which is a strong function of temperature: at 95Β°C, approximately Eh = 400, at 25Β°C at approximately E~ = 600 mV (potentials against reversible H2-electrode).
This adsorption peak is ascribed to the oxidation of an intermediate, which was reported previously to be also formed by reduction of COs and which we call "reduced COs" (possibly it is CO or COOH).
Here this species is formed by partial oxidation of methanol or formic acid and to some extent by decomposition of these reactants at open circuit. Below the potential of the peak this species accumulates on the electrode and blocks further oxidation of the reactant; above the potential of the peak the species is oxidized to CO, faster than it is being produced, freeing the surface for continuous oxidation.
The same results apply qualitatively to bright platinum.
R6sum6--Sur la courbe anodique de balayage rapide du platine platin6, dans des solutions acides (CH3OH + HCOsH), il apparait un pie d'adsorption, d6pendant fortement de la temp&ature (400 mV ~t 95Β°C et 600 mV ~-25Β°C, par rapport ~t 61ectrode ~, hydrog/~ne). Il est attribu6 h l'oxydation d'un interm6diaire, pr6c6demment signal6 pour la r6duction de COs (peut-6tre CO ou CO,H). La mEme esp/~ serait ici due/~ l'oxydation partielle de CHaOH ou de HCOsH et (dans une certaine mesure) la d6composition de ces corps en circuit ouvert. Au dessous de la tension du pic, ces constituants s'accumulent sur l'61ectrode, bloquant l'oxydation ult6rieure. Au dessus, l'oxydation en COs est plus rapide que la production de corps oxydable, ce qui libere la surface pour un processus continu. Les n6mes constatations peuvent ~tre faites qualitativement sur le platine poli.