Effect of ionic composition of solutions on the methanol reaction with adsorbed oxygen on smooth polycrystalline platinum electrodes: Transients of the open-circuit potential

Transients of the open-circuit potential observed in the reaction of methanol with oxygen (O-ads) preliminarily adsorbed on smooth polycrystalline platinum (pcPt) are measured in 0.05 M HClO4, 0.5 M HClO4, 0.05 M H2SO4, 0.05 M H2SO4 + 0.45 M Na2SO4, and 0.05 M H2SO4 + 0.45 M Cs2SO4. It is shown that the solution pH has a weak effect on the transient characteristics (when the reversible hydrogen electrode potential scale is used). This confirms the chemical nature of rate-controlling stages in the reaction mechanism. The changes in the reaction rate, observed upon going from one electrolyte to another, are preferentially associated with the involvement of solution ions in the formation of activated surface complexes that include CH3OH, O-ads, and supporting-electrolyte components.