A glassy carbon electrode modified with a film composed of cobalt oxide nanoparticles and graphene for electrochemical sensing of H2O2

We have prepared a graphene-based hybrid nanomaterial by electrochemical deposition of cobalt oxide nanoparticles (CoO(x)NPs) on the surface of electrochemically reduced graphene oxide deposited on a glassy carbon electrode (GCE). Scanning electron microscopy and cyclic voltammetry were used to characterize the immobilized nanoparticles. Electrochemical determination of H2O2 is demonstrated with the modified GCE at pH 7. Compared to GCEs modified with CoO(x)NPs or graphene sheets only, the new electrode displays larger oxidative current response to H2O2, probably due to the synergistic effects between the graphene sheets and the CoO(x)NPs. The sensor responds to H2O2 with a sensitivity of 148.6 mu A mM(-1) cm(-2) and a linear response range from 5 mu M to 1 mM. The detection limit is 0.2 mu M at a signal to noise ratio (SNR) of three. The method was successfully applied to the determination of H2O2 in hydrogen peroxide samples.