The proposed mechanism of this reaction involves hydrogen peroxide acting as a reducing agent (Reaction R1), providing an electron to the diazonium salt to generate aryl radicals (Reaction R2), which subsequently react with the nanotube surface to generate sp 3 defect sites. The performance of hydrogen peroxide as a reducing agent is highly pH-dependent; as described in Reaction R1, the oxidation of hydrogen peroxide to oxygen generates protons, the neutralization of which shifts the equilibrium towards the release of electrons. At low pH values, hydrogen peroxide is more likely to act as an oxidizing agent (Side Reaction SR1), generating hydroxyl radicals which can potentially react with nanotubes to form undesirable oxygen-based sp 3 defects. Conversely, the stability of diazonium salts decreases at higher pH, as diazonium groups are susceptible to nucleophilic substitution driven by release of nitrogen gas (Side Reaction SR2). Both Reactions R1 and R2 are driven by the release of gas, which provides an entropic driving force.