Fig. 5

Theoretical calculations. Models (top) and the corresponding free energy diagrams (bottom) for cycled carbon atoms at electrode potential UNHE = 0 and 0.745 V in 0.5 M H2SO4 (NHE normal hydrogen electrode, RHE reversible hydrogen electrode, UNHE = URHE − 0.0591 × pH, pH = 0.25). a Carbon atom at zigzag edge, b carbon atom in basal plane, c carbon atom at O-doped zigzag edge, d carbon atom at armchair edge, and e carbon atom near a void