Enzyme-free glucose sensor using a glassy carbon electrode modified with reduced graphene oxide decorated with mixed copper and cobalt oxides

We describe a binary porous catalyst consisting of a reduced graphene oxide (rGO) support decorated with mixed Cu-Co oxides. It was synthesized electrochemically and characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry. The nanocomposite was deposited on a glassy carbon electrode (GCE) where it exhibits better electrocatalytic activities for glucose oxidation compared to GCEs modified with CuOx or CoOx only on an rGO support. The improved electrocatalytic activities are believed to result from the synergistic effect of CuOx-CoOx binary catalyst, the high conductivity of rGO support, and the porous scaffold. The amperometric sensor, operated in 0.1 M NaOH at a working potential of +0.5 V (vs. SCE), displays a calibration plot for glucose that is linear in the 5 to 570 mu M concentration range, and the detection limit is 0.5 mu M. The performance of the sensor was evaluated by determination of glucose in (spiked) human urine.