Figure 2.

(a) Static image of electrochemical activity (proton transmission), collected over a 100 × 100 μm² area of the graphene|Nafion membrane, using SECCM in the voltammetric (υ = 0.1 V s^–1, 1 cycle) hopping mode configuration (hopping distance = 2 μm, 51 × 51 pixels, tip area ≈1 μm²). This image was obtained by integrating (with respect to time) the spatially resolved |i_surf| data from SI Movie S1, over the entire E_surf range (−0.225 to 0.175 V vs Ag/AgCl_QRCE). (b–i) Spatially resolved CVs (i_surf–E curves), obtained by (b) averaging all inactive pixels (N = 2582) or (c–i) from the individual (representative) active pixels, indicated in (a). The border of each CV in (b–i) corresponds to the corresponding pixel colors in (a). Note that in (a), pixels with log₁₀|Q| values less than 3× the electrical noise level are assigned a gray color and are considered to be inactive.