Overlapping charge densities, oxides

However, there are really two distributions of electronic energy levels associated with redox, due to the fact that O and R, having different charges, have different solvations the energy of R is slightly lower than that of O. The density of states is shown schematically in Fig. 4.6. Overlap between EF and the distribution for E0 shows that oxidized species can be reduced. 

The presence of other cathodic and anodic peaks points to electrochemical activity on other oxygen species existing on the carbon surface (see Table 4). Additionally, they may be overlapped by a significant capacitive current [153]. However, it should be remembered that the real chemical structure of an oxidized carbon surface [101] depends on the hydrolysis of lactone-, ester- or ether-like anhydrous systems and the ionization of some functionalities at extreme pH values (acidic or basic environments) [91]. These phenomena influence the surface density of species that can take part in charge-transfer processes, which explains the observed differences in height of reduction peak in different environments (see Fig. 18). These relationships can account for the reactions, e.g. [7,14,148],... 

---