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Electrochemically reduced graphene oxide (ERGO) based voltammetric sensors have drawn considerable attentions due to their simple preparation process and outstanding electrochemical properties. While quite a lot of work suffers from problems in terms of sensitivity and cycling stability. Here, we demonstrate that the reduction extent of ERGO displays a crucial role in enhancing sensitivity and preventing electrode fouling. To illustrate this, partially reduced and relatively complete reduced ERGO films were prepared via the electrochemical method. The reduction extent was controlled by performing cyclic voltammetry with varieties of reduction cycle numbers. Results indicated that partially reduced ERGO film with 5 reduction cycle numbers (ERGO 5 ) showed the highest sensitivity towards electrochemical oxidation of isoniazid (INZ) among all the ERGO films with different reduction extents, and acquired better electrode stability as compared with ERGO 15 . Under the optimal conditions, the peak currents on ERGO 5 modified electrode increased linearly with the concentrations of INZ in the range of 0.09–100 μM. The detection limit of INZ reached 15 nM (S/N = 3). The present work has a guidance meaning in developing ERGO based sensors for detecting other electroactive analytes. [ABSTRACT FROM AUTHOR]

Cu nanoparticle/graphene oxide/single walled carbon nanotube (CuNP/GO/SWCNT) composites were prepared by a facile electrodeposition method and used for constructing nonenzymatic glucose sensor. Scanning electron microscopy (SEM) and Raman spectroscopy were employed to characterize the morphology and structures of the samples. The electrocatalytic performance of CuNP/GO/SWCNT composites towards glucose oxidation was studied by cyclic voltammetry (CV) and current–time measurements. Electrochemical results indicated that CuNP/GO/SWCNT electrode exhibited a higher electrocatalytic activity towards the oxidation of glucose than CuNP, CuNP/GO and CuNP/SWCNT electrodes. This was because the GO/SWCNT composite as substrate material not only possessed excellent conductivity, but also provided large surface area for the high loading of the CuNPs. Meanwhile, the good dispersibility, independent and multi-layer structure of CuNP, could enhance the charge-transport properties, and afford more active sites for the catalytic oxidation of glucose. Under the optimized conditions, the sensor showed a high sensitivity of up to 930.07 μA mM − 1 cm − 2 , with a wide linear range of 1 μM to 4.538 mM and a low detection limit of 0.34 μM (S/N = 3). It also exhibited excellent stability, reproducibility, selectivity, and reliable measurement in real human blood samples. All of these excellent properties made the CuNP/GO/SWCNT composite material promising for the development of effective nonenzymatic glucose sensors. [ABSTRACT FROM AUTHOR]