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The authors describe a nonenzymatic glucose sensor that was obtained by electrochemical deposition and oxidization of metallic nickel on the surface of nitrogen-doped reduced graphene oxide (N-RGO) placed on a glassy carbon electrode (GCE). An analysis of the morphology and chemical structure indicated the composite to possess a well-defined vermicular Ni(OH) nanorods combined with N-RGO. The electrochemical performance of the modified GCE with respect to the detection of glucose in 0.1 M NaOH was investigated by cyclic voltammetry and amperometry. The wrinkle and protuberance of N-RGO for loading of nanostructured Ni(OH) are found to increase electrical conductivity, surface area, electrocatalytical activity and stability. The modified GCE displays a high electrocatalytic activity towards the oxidation of glucose in 0.1 M NaOH solution. The lower detection limit is 0.12 μM at an applied potential of +0.45 V (vs Ag/AgCl) (S/N=3), and the sensitivity is 3214 μA mM cm. The modified GCE possesses long-term stability, good reproducibility and high selectivity over fructose, sucrose and lactose. [ABSTRACT FROM AUTHOR]

Ultrasensitive explosive sensors are significant in anti-terrorism and related environment issues. Herein, we proposed a novel boron-doped graphene (B-GE) modified glassy carbon electrode (GCE) applied as a simple, sensitive electrochemical high melting explosive (HMX) sensor. The morphology and structure features of B-GE were characterized. The electrochemical behaviors of HMX on the B-GE modified GCE were investigated by cyclic voltammetry (CV). Under the optimized conditions, CV was used for the quantitative detection of HMX, and the reduction peak current exhibited good linear dependence with the concentration of HMX in the ranges of 2 ∼ 20 μM and 20 ∼ 100 μM. The low detection limit (LOD) was calculated as 0.83 μM (245.81 ppb). Furthermore, the B-GE/GCE showed satisfactory repeatability, high selectivity and stability. The reduction reaction mechanism of HMX on B-GE modified electrode was explored by computational theoretical analysis. Additionally, the differences of the reduction mechanisms from nitroaromatic explosives were discussed. [ABSTRACT FROM AUTHOR]

Abstract: Polycarbazole (PCz) and PCz/chemically reduced graphene oxide (PCz/CRGO) modified glassy carbon electrodes (GCEs) were fabricated by a simple procedure and characterized. The modified electrodes based on PCz or PCz/CRGO were used as sensing electrodes for the voltammetric investigation of imidacloprid (IMI) insecticides. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used as sensing techniques. Both of modified electrodes have good electrocatalytic activity toward the reduction of IMI. The presence of CRGO enhanced the electrochemical signal of the modified glassy carbon electrode (GCE), which increased the sensitivity of the sensor. The limit of detection (LOD) and the limit of quantitation (LOQ) values for CV are 0.22μM and 0.74μM, respectively; while those values for DPV are 0.44μM and 1.52μM, respectively. [Copyright &y& Elsevier]

Polycarbazole (PCZ)/nitrogen-doped graphene (N-GE) composite was prepared by electropolymerization of carbazole on the N-GE modified glass carbon electrode (N-GE/GCE) for fabricating a novel electrochemical sensor for 4-nitrophenol (4-NP). The PCZ/N-GE shows high conductivity and well-distributed nanostructure. The redox behavior of 4-NP at a PCZ/N-GE/GCE was investigated in acetate buffer solution by cyclic voltammetry (CV), compared with the bare GCE, reduced graphene oxide (RGO), N-GE and PCZ modified GCEs. The results indicate that all modified electrodes show the enhanced reduction peak currents. However, the PCZ/N-GE/GCE exhibits the highest peak current and most positive reduction potential of 4-NP, which reflects the PCZ/N-GE composite has the best electrocatalytic activity towards 4-NP. The enhanced electrochemical performance of PCZ/N-GE and the electrocatalytic activity to 4-NP are contributed to the synergic effect of PCZ and N-GE with highly conductivity and large surface area, which can greatly facilitate the electron-transfer processes between the electrolyte and electrode. An electrochemical sensor for 4-NP was developed based on the PCZ/N-GE modified electrode under the optimized conditions. The reduction peak current was linear with the concentration of 4-NP in the range of 8 × 10 -7 ∼2 × 10 -5 M. The low detection limit of the sensor was estimated to be 0.062 μM (S/N = 3). The sensor based on PCZ/N-GE/GCE was also applied to the detection of 4-NP in real water samples. [ABSTRACT FROM AUTHOR]

Metal oxides decorated carbon nanomaterials, as an electrode material have been well explored in the field of electrochemical sensor. However, instead of using the high concentration of graphene oxide (GO), we try to explore the influence of minimum quantity of GO in material synthesis. Here we demonstrate the hydrothermal synthesis of low-cost cerium (Ce)-doped tungsten oxide/graphene oxide (CeW/GO) composite for the precise electrochemical detection of antibiotic drug furazolidone (FUZ). For the synthesis of composite, 40 μg/mL concentration of GO has been utilized. Then, several physicochemical and electrochemical techniques were used to examine the morphological, structural, and electrochemical characteristics of the CeW/GO composite. Interestingly, the composite material has a porous-coral-like structure, which is being described here for the first time. The GO nanosheets cover the CeW and make the smooth surface and lead to the porous structure. Then we looked into the analytical behavior of CeW/GO composite modified glassy carbon electrode for the application towards the electrochemical detection of the FUZ using the voltammetric technique. The effect of experimental conditions, including loading concentration of active material, pH, scan rate, accumulation time, and concentration of FUZ, were analyzed with respect to the reduction peak current response of FUZ. At the optimum conditions, the fabricated sensor has a low detection limit (0.054 μM), appreciable sensitivity (2.5 μA μM−1 cm−2) with a wide linear range (1–260 μM), and the decent anti-interference ability for FUZ detection. Furthermore, the developed sensor was successfully used to assess the FUZ concentration in the human urine samples, yielding satisfactory results. [Display omitted] • porous-coral-like CeW/GO micro balls composite material was designed for the first time. • The CeW/GO composite was employed as a novel electrocatalyst to detect the furazolidone (antibiotic drug). • A detailed study was made on electrochemical performance of the developed sensor. • The performance of CeW/GO/GCE was comparable with the noble metals (Pt, Re, and Au) based modified electrodes. [ABSTRACT FROM AUTHOR]