Unfortunately, the CV peak for O* → OH* overlaps with that of OH* desorption, leading to the broad reduction peak at ~0.8 V at the scan rate of 50 mV/s or above (Figure ). To differentiate these two processes, CVs were collected at lower scan rates. Indeed, a separate reduction peak attributable to the Onormal → OHnormal transition becomes visible in the cathodic scan at the scan rate of 10 mV/s or below 10 mV/s on the bare Pt(111) in 0.1 M HClO4 (Figure ). In contrast, separation of reduction peaks of ONafion → OHNafion and OHNafion → OH -cannot be achieved even at 5 mV/s (Figure ), indicating the slower Quantitative charge analysis suggests that there is an additional type of interaction between Nafion and Pt(111) aside from the specific adsorption of sulfonate. With the sulfonate coverage increasing from 0.022 ML to 0.048 ML, the amounts of charges attributable to specific anion adsorption (OH -and sulfonate)