Cation effects on the electro-oxidation of alcohols are not mediated solely by their interactions with adsorbed OH

In this work, we deconvolute the impact of electrolyte cations on the electro-oxidation of glycerol on Pt. UV-Vis reflectograms reveal that the presence of glycerol inverts and enhances the magnitude of cation effects on Pt oxidation. A cation-dependent glycerol diffusion coefficient was then identified using ¹ H-DOSY-NMR, providing solid experimental evidence that smaller cations interact more strongly with glycerol than larger ones. The rates of partial oxidation of glycerol to adsorbed carbon monoxide (CO _ad ), and of CO _ad oxidation, measured as a function of cation identity using time-resolved ATR-SEIRAS, suggest that global cation-induced trends in GOR activity are driven mainly by the reaction pathways that do not involve CO _ad . This implies that interactions between electrolyte cations and AOS alone cannot explain the cation-induced trends in electrocatalytic behaviour. Instead, the interactions of electrolyte cations with the reactant are critical to the cation-dependent electrocatalytic activity of alcohol and polyol oxidation.