Electrodeposition of cobalt oxide nanoparticles on reduced graphene oxide: a two-dimensional hybrid for enzyme-free glucose sensing

Based on the extraordinarily properties of graphene, cobalt oxide nanoparticles (CoO (x) NPs)/graphene-modified electrode was prepared by electrodeposition of CoO (x) NPs on the glassy carbon surface previously modified with electrochemically reduced graphene oxide (ERGO), which was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy. It was found that a large amount of CoO (x) NPs with diameter less than 100 nm was uniformly grown on the surface of graphene nanosheets. The as-prepared CoO (x) NPs/ERGO hybrids were applied to construct an enzyme-free sensor for glucose detection in alkaline solution. The developed glucose sensor shows a short response time (less than 5 s), a high sensitivity of 79.3 mu A mM(-1) cm(-2), a detection limit of 2 mu M (S/N = 3), and good selectivity to prevent from the interference of some species including ascorbic acid, uric acid, dopamine, and sodium chloride. Importantly, favorable reproducibility and long-term performance stability were also obtained. Application of the proposed sensor in monitoring urine glucose was also demonstrated.