Figure 4.

(A) Nyquist plots obtained for G-CN (orange line), GA1 (black line), and GA2 (blue line) using a rotating disk electrode in an Ar-saturated PBS 0.1 M (pH = 7) electrolyte with 25 mmol of H₂O₂ at −0.4 V vs SCE; the left inset shows the equivalent circuit used for fitting where R_s is the solution resistance, and the subsequent (resistor, constant phase element, CPE) components are associated with the charge-transfer resistance in parallel with the double layer capacitance (R₁, CPE1) and the resistance related to diffusion processes (R₂, CPE2 and R₃, CPE3). The right inset shows a magnification of the high frequency part of the Nyquist plot where the charge-transfer processes take place. (B–D) Optimized structures of complexes of graphene derivatives (in water) (B, GA; C, G-CN; and D, GO) with H₂O₂. The hydrogen bonds between H₂O₂ and graphene functional groups are indicated by yellow dashed lines. The interaction energies in kcal mol^–1 between H₂O₂ and graphene derivatives are stated below each structure.