Understanding the reaction mechanism of the reactivity of free radicals with graphene oxide

On pulse irradiation of an aqueous solution containing graphene oxide (GO), hydrated electrons (eaq−) are captured by GO in microsecond time scales as suggested recently (ref. 26). We have observed low reactivity of eaq− towards GO as compared to the reported value. It is shown here that the effect of pH (6.8 - 9.2) on the reactivity of eaq− with GO is not significant. The effect of solvent on the reactivity of GO towards free radical was also studied. No significant change in the decay kinetics of MV+
- radical in the presence of GO was observed under our experimental conditions. Quenching of eaq− or solvated electron (esol−) in aqueous solution and ethanol, respectively, by GO is confirmed by decrease in the yield of MV+
- radical in its presence. In ethanol suspension, the decrease in the rate of formation of MV+
- was also observed. It appears that ethanol radicals also transfer electron to MV2+ and GO. Further, to substantiate the formation mechanism of reduced graphene oxide by phenols and amino acids, the pulse radiolysis experiments were carried out and it was observed that phenoxyl radicals as well as tryptophan radicals do not react with GO.