Fabrication of a Highly Sensitive Hydrazine Electrochemical Sensor Based on Bimetallic Au-Pt Hybrid Nanocomposite onto Modified Electrode

In this research a novel nickel complex was used as electrocatalyst for electrooxidation of hydrazine.A nano-structured nickel-complex was electrodeposited on a bimetallic Au-Pt inorganic-organic hybrid nanocomposite modified electrode.The electrode possesses a three-dimensional(3D) porous network nanoarchitecture,in which the bimetallic Au-Pt NPs serving as metal nanoparticle based microelectrode ensembles are distributed in the matrix of interlaced 3,3′,5,5′-Tetramethylbenzidine(TMB) organic nanofibers(NFs).Surface structure and composition of the sensor was characterized by scanning electron microscopy.Electrocatalytic oxidation of hydrazine on the surface of modified electrode was investigated with cyclic voltammetry method.The results showed that the nickelcomplex films displayed excellent electrochemical catalytic activities towards hydrazine oxidation.The hydrodynamic amperometry at rotating modified electrode at constant potential versus reference electrode was used for detection of hydrazine.Under optimized conditions the calibration plots were linear in the concentration range of 0.2-85 μM and detection limit was found to be 0.1 μM.The modified electrode exhibited reproducible behavior and a high level stability during the electrochemical experiments,making it particularly suitable for the analytical purposes.

The Electrochemical Behavior of Au/Au NPs/PNA/ZnS e-QD/ACA Electrode Towards Cy SH Oxidation

This work describes the electrochemical behavior of azodicarboxamide(ACA) film immobilized on the surface of penicillamine(PNA)/Zn Se-quantum dot(Zn Se-QD) gold nanoparticle(Au NPs) Au electrode. Electrocatalytic activity of modified electrode toward the oxidation of cysteine(Cy SH) was investigated. The surface structure and composition of the sensor were characterized by scanning electron microscopy(SEM). Oxidation of Cy SH on the surface of modified electrode was investigated with cyclic voltammetry, electrochemical impedance spectroscopy(EIS),hydrodynamic voltammetry and chronoamperometry methods. The results show that the PNA/Zn Se-QD/ACA film displays excellent electrochemical catalytic activities towards Cy SH oxidation. The modified electrode shows reproducible behavior and high level of stability during the electrochemical experiments. Also it has short response time, low detection limit, high sensitivity and low operation potential, which can be used as an amperometric sensor for monitoring of Cy SH. The proposed modified electrode was successfully used for determination of Cy SH in real sample such as human serum.

Surface-Renewable AgNPs/CNT/rGO Nanocomposites as Bifunctional Impedimetric Sensors

In this study, glassy carbon electrode modified by silver nanoparticles/carbon nanotube/reduced graphene oxide(AgNPs/CNT/rGO) composite has been utilized as a platform to immobilize cis-dioxomolybdenum(VI)–salicylaldehydehistidine(MoO_2/Sal-His). The modified electrode shows two reversible redox couples for MoO_2/Sal-His. Electrocatalytic oxidation of cysteine(CySH) and electrocatalytic reduction of iodate on the surface of the modified electrode were investigated with cyclic voltammetry and electrochemical impedance spectroscopy methods. The presence of MoO_2/SalHis on AgNPs/CNT/rGO shifted the catalytic current of iodate reduction to a more positive potential and the catalytic current of cysteine oxidation to a more negative potential. The change of interfacial charge transfer resistance(R_(ct))recorded by the modified electrode was monitored for sensitive quantitative detection of CySH and iodate. Moreover, the sensor has a good stability, and it can be renewed easily and repeatedly through a mechanical or electrochemical process.