Tuning the electrochemical reduction of graphene oxide: structural correlations towards the electrooxidation of nicotinamide adenine dinucleotide hydride

This work demonstrates for the first time the effect of tuning the electrochemical reduction of graphene oxide (GO) on its electrocatalytic properties towards the electrooxidation of NADH. The investigations of differently tuned electrochemically reduced graphene oxide (ERGO) allowed the obtainment of clear evidences that groups containing C=O and/or C-O functionalities are responsible for this electrocatalytic response of the nanomaterial. The electrochemical reduction of GO was conducted by chronoamperometry. The ERGO-modified electrodes were characterised by Raman and X-ray photoelectron spectroscopy (XPS). The redox signals of the ERGO films in the presence of NADH have shown a completely different trend when compared to ferri/ferrocyanide, indicating that the electroactivity goes beyond electrical features of ERGO, with some oxygenated functional groups playing a vital role. We show that the presence of these groups depends on the manner in which the electrochemical reduction of GO was performed, and they are responsible for the electrocatalytic activity towards the electrooxidation of NADH. Our results show the influence of C-O/C=O containing functional groups, which are the same groups involved in the reaction between NADH and quinones.