Nickel-cobalt nanostructures coated reduced graphene oxide nanocomposite electrode for nonenzymatic glucose biosensing

Nickel-cobalt nanostructures (Ni-Co NSs) electrodeposited on reduced graphene oxide (RGO)-modified glassy carbon electrode (GCE) was prepared and used for highly sensitive glucose detection. RGO nanosheets were firstly assembled onto GCE surface by pi-pi interaction and then Ni-Co NSs were constructed on RGO/GCE by dynamic potential scan. The electrochemical and electrocatalytic behaviors of the Ni-Co NSs/RGO/GCE toward glucose oxidation were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. The effects of some factors related to the fabrication of Ni-Co NSs/RGO/GCE, such as potential scan number and the molar ratio of Ni2+/Co2+ in a solution, on the catalytic performance of the Ni-Co NSs/RGO/GCE were also explored. The results showed that the Ni-Co NSs/RGO/GCE exhibited the best catalytic activity at the potential scan number of 20 and the Ni2+/Co2+ molar ratio of 1:1. The glucose concentration in the range of 10 mu M to 2.65 mM linearly depended on the catalytic current (r = 0.9967, n=17). The sensitivity was 1773.61 mu A cm(-2) mM(-1), and the detection limit was 3.79 mu M (S/N = 3). This high catalytic activity, good sensitivity and stability of the Ni-Co NSs/RGO/GCE sensor opened up a new kind of hybrid materials in electrochemical detection of glucose. (C) 2013 Elsevier Ltd. All rights reserved.