Redox-active water-soluble carbon nanomaterials generated from graphite

Abstract

The cyclic voltammetric response of the anolyte generated under strong polarization of graphite electrodes in a phosphate solution was investigated to evaluate the intrinsic electrochemical activity of water-soluble carbon-based nanomaterials contained in it. Two electroreducible oxygen-containing functional groups were identified: quinone and epoxide. Since the nanomaterial was found to be surface-bounded to the electrode, the surface coverage of quinone and epoxide groups was quantified to appraise the effect of synthesis experimental conditions on the relative amounts of the two functionalization groups. The synthesis conditions were investigated in terms of the electrolytic solution composition (ionic strength and pH) and duration of the graphite polarization under galvanostatic polarization. Most appropriate experimental conditions to generate quinone rather than epoxide moieties (Γ quin /Γ ep = 2.5) were found when the nanomaterial was generated in a 3 h-assay using a neutral pH phosphate solution with low ionic strength (I = 0.1). These results may be taken as a guideline to modulate the redox-active water-soluble carbon nanomaterial functionalization, opening new perspectives to its application in sensing, energy storage, and nanomedicine.