are identical within the experimental uncertainty (Figure ). Intriguingly, the anodic adsorption charge with Nafion is ~20% less than that on the bare Pt(111). Since the sulfonate coverage does not impact the overall charge attributed to anion (OH -and sulfonate) specific adsorption, the difference between the charge attributed to anion adsorption with and without specific adsorption of sulfonate must be due to the presence of the polymer backbones and side chains of Nafion. The presence of hydrophobic polymeric components is likely to suppress OH adsorption, which is not the case in the Hupd region (Figure ). Nafion's backbone is made of polytetrafluoroethylene (PTFE). Interestingly, CV on PTFE-covered Pt(111) shows quite different features from that on Nafion-covered surface (Figure ), i.e., CV features in both Hupd and hydroxide regions are severely suppressed. The differences in the CVs on PTFE-and Nafion-covered Pt (111) show that the mode of interaction between polymer and the electrode surface is dominated by the presence or absence of sulfonate groups. In the presence of sulfonate groups, the PTFE backbone cannot effectively impact the adsorption and desorption of surface species, e.g., Hupd and OH, likely because the polymer backbone is mostly spatially removed from the EDL. In contrast, interaction of the polymer backbone with adsorbates is more pronounced on PTFE-covered Pt(111).