Figure 7.

(a) Electrochemically measured LSV of N-graphene catalyst at different rotating speeds in an O₂-saturated 0.1 M solution of KOH. Inset illustrates the last electron transfer step: OH* desorption to generate OH^–. (b) Koutecky–Levich plots for N-graphene at −0.3 V, −0.2 V, and −0.1 V vs NHE, data were collected from panel a. (c) Potential corrected free energy diagram for gN-G and X-graphene models at U^RHE = 0 V (U^NHE = −0.77 V). (d) The relationship between ΔG_OH* and j_K for various synthesized graphene catalysts under different potentials (open symbols), data were collected from Figure S3, SI. The values in parentheses of the legend are j_K values for X-graphene, which are predicted by extending the fitted lines to ΔG_OH* = 0.10 eV, shown as closed symbols.