Glassy carbon electrode modified with a film composed of Ni(II), quercetin and graphene for enzyme-less sensing of glucose

We present a modified glassy carbon electrode as a sensing platform for glucose. It is based on a composite film prepared from Ni(II) ion, quercetin and graphene. The sensor was characterized by cyclic voltammetry. The electron transfer coefficient, reaction rate constant and catalytic rate constant were determined and found to be 0.53, 5.4 s −1 and 2.93 × 10 3  M −1 s −1 , respectively. The catalytic current depends linearly on the concentration of glucose in the range from 3 to 900 μM, with a detection limit of 0.5 μM (at an S/R of 3). The sensor exhibits good reproducibility, stability, fast response, and high sensitivity. Cyclic voltammograms of Ni(II)-Qu/Gr/GCE in 0.1 M NaOH solution at various scan rates (from inner to outer): 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 V·s −1 . Plot of I p versus υ 1/2 and E p versus logυ.