Sensitive and selective determination of hydrazine using glassy carbon electrode modified with Pd nanoparticles decorated multiwalled carbon nanotubes

A glassy carbon electrode modified with palladium nanoparticles decorated multiwalled carbon nanotubes (GCE/nanoPd-MWCNTs) was fabricated. Incorporation of palladium nanoparticles onto the carbon nantube surface by thermal decomposition of palladium acetate led to the fabrication of a sensor with a significant decrease in hydrazine electrooxidation potential. The sensor exhibited low detection limits, high sensitivity and selectivity, rapid response, and good stability toward hydrazine detection.     

A glassy carbon electrode modified with carbon nanotubes and reduced graphene oxide decorated with platinum-gold nanoparticles for voltammetric aptasensing of urea

This article reports on a novel aptamer-based platform for the quantitation of urea by using an aptamer with high affinity and selectivity for urea. The surface of a glassy carbon electrode (GCE) was modified by drop casting a cocktail consisting of carbon nanotubes and reduced graphene oxide (rGO) decorated with platinum-gold nanoparticles. The urea aptamer was then immobilized on the nanocomposite via covalent conjugation. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to trace the modification of the GCE. Binding of urea caused the aptamer to be folded, and this result in an inhibition of the interfacial charge transfer rate when using hexacyanoferrate as an electrochemical redox probe. The change in redox current was quantified by differential pulse voltammetry, typically at a working voltage of 0.22 V vs. Ag/AgCl. The assay has a 1.9 pM detection limit, and the response is linear up to 150 nM concentration of urea. The superior selectivity and affinity of aptamer-modified GCE makes it a most useful tool for analysis of urea present in very low concentrations.

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Graphical abstract Schematic representation of different steps of aptasensor fabrication.

     

石墨烯修饰玻碳电极伏安法测定酪氨酸

制备了石墨烯修饰玻碳电极,研究了酪氨酸在修饰电极上的电化学行为.优化了包括支持电解质、溶液pH、修饰剂用量、富集电位及时间等测定条件.在0.1 mol·L-1pH 7.0的磷酸盐缓冲溶液中,峰电流与酪氨酸的浓度在3×10-6～1.2×10-4mol·L-1的范围内呈良好的线性关系,检出限为2 × 10-7 mol·L-...     

A glassy carbon electrode modified with graphene quantum dots and silver nanoparticles for simultaneous determination of guanine and adenine

Microchimica Acta - A glassy carbon electrode (GCE) was modified with graphene quantum dots (GQDs) carrying silver nanoparticles. The modified GCE displays excellent performance in the...     

Reduced graphene sheets modified glassy carbon electrode for electrocatalytic oxidation of hydrazine in alkaline media

This paper describes the electrochemical properties of reduced graphene sheets (RGSs) for the electrocatalytic properties towards the hydrazine oxidation in alkaline media. The RGSs have been produced in high yield by a soft chemistry route involving graphite oxidation, ultrasonic exfoliation, and chemical reduction. The RGSs possess excellent electrocatalytic activity towards the hydrazine oxidation. In our opinion, RGSs are a potential electrode material for direct hydrazine fuel cells and electrochemical sensors for hydrazine detection.     

石墨烯修饰玻碳电极伏安法测定美洛昔康

通过在玻碳电极表面电化学还原氧化石墨烯的方法制备了石墨烯修饰电极,研究了美洛昔康在该修饰电极上的电化学行为。优化了包括支持电解质及pH、修饰剂用量、富集电位及时间等测定条件,据此建立了一种直接测定美洛昔康的电化学分析方法。在0.1 mol/L Britton-Robinson缓冲液(pH 3.0)中,氧化峰电流与美洛昔康浓度在1.0×10-6～8.0×10-5mol/L范围内呈现良好的线性关系,检出限为3.0×10-7mol/L(S/N=3)。方法可用于片剂和尿样中美洛昔康的测定。     

Electrochemical detection of selenium using glassy carbon electrode modified with reduced graphene oxide

In this work, a simple experimental procedure was reported for the electroanalytical determination of selenium (IV) using reduced graphene oxide (rGO) to modify glassy carbon electrode (GCE). The rGO was obtained by reduction of graphene oxide obtained via Hummer’s method. The synthesised rGO was characterised using X-ray diffraction, Raman spectroscopy, scanning electron microscope (SEM), energy-dispersive spectroscopy and transmission Electron microscopy (TEM). GCE was modified with rGO and the electrochemical properties of the bare and modified electrode were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The results obtained showed that the modified electrode exhibited more excellent electrochemical properties than the bare GCE. The optimum conditions for detection of selenium in water using square wave anodic stripping voltammetry were as follows: deposition potential ?500 mV, pH 1, pre-concentration time of 240 s and 0.1 M nitric acid was used as supporting electrolyte. The linear regression equation obtained was I (µA) = 0.8432C + 9.2359 and the detection limit was calculated to be 0.85 μg L^?1. However, Cu(II) and Cd(II) are the two cations that interfered in the analysis of selenium in water.

The sensor was also applied for real sample water analysis and the result obtained was affirmed with inductively coupled plasma optical emission spectroscopic method. It is believed that our proposed sensor hold promise for practical application.     

An amperometric sensor for hydrazine based on nano-copper oxide modified electrode

A sensitive hydrazine sensor has been fabricated using copper oxide nanoparticles modified glassy carbon electrode (GCE) to form nano-copper oxide/GCE. The nano-copper oxide was electrodeposited on the surface of GCE in CuCl₂ solution at −0.4 V and was characterized by Scanning electron microscopy and X-ray diffraction. The prepared modified electrode showed a good electrocatalytic activity toward oxidation of hydrazine. The electrochemical behavior of hydrazine on nano-copper oxide/GCE was explored. The oxidative current increased linearly with improving concentration of hydrazine on nano-copper oxide/GCE from 0.1 to 600 μM and detection limit for hydrazine was evaluated to be 0.03 μM at a signal-to-noise ratio of 3. The oxidation mechanism of hydrazine on the nano-copper oxide/GCE was also discussed. The fabricated sensor could be used to determine hydrazine in real water.     

A glassy carbon electrode modified with gold nanoparticle-encapsulated graphene oxide hollow microspheres for voltammetric sensing of nitrite

Reduced graphene oxide hollow microspheres (rGO HMS) were encapsulated with gold nanoparticles (AuNPs) by spray drying. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the AuNP/rGO HMS. When placed on a glassy carbon electrode (GCE), it exhibits excellent electrochemical catalytic properties towards the oxidation of nitrite. The electrocatalytic properties were studied using various electrochemical techniques. Compared to AuNP-decorated graphene sheet based electrodes documented in the literature, the one presented here provides a larger surface area. This enhances the catalytic activity towards nitrite. The electrode, typically operated at a working potential of 0.82 V (vs. SCE), has a linear response in the 5.0 μM to 2.6 mM nitrate concentration range, and a detection limit as low as 0.5 μM (at an S/N ratio of 3).

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Graphical abstract Schematic presentation of the synthesis of graphene hollow microspheres encapsulated with of gold nanoparticles (AuNP/rGO HMS) through a spray drying technique. The material was applied to the electrochemical determination of nitrite.

     

A glassy carbon electrode modified with poly(3,4-ethylenedioxythiophene) doped with nano-sized hydroxyapatite for amperometric determination of nitrite

A conducting polymer composite was prepared from nano-sized hydroxyaptite (nHAp) doped into poly(3,4-ethylenedioxythiophene) (PEDOT) and then electrodeposited on a glassy carbon electrode (GCE). The nHAp carries carboxy groups and therefore is negatively charged at moderate pH value. When doped into PEDOT (PEDOT-nHAp), it forms a uniform and stable film that exhibits low electrochemical impedance, a large specific surface, and high activity toward the electrochemical oxidation of nitrite. Under optimized conditions and at a relatively low working potential of 0.78 V (vs. SCE), the modified GCE exhibited a linear amperometric response in the 0.25 μM to 1.05 mM nitrite concentration range, and the limit of detection is as low as 83 nM.

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Graphical abstract A highly sensitive nitrite sensor was developed based on conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with carboxyl group functionalized hydroxyapatite nanoparticles, which exhibited a large surface area and good conductivity and stability.