Behavior Of Glassy Carbon Electrode Research Articles

Electrochemical sensor based on polyaniline supported CdS/CeO2/Ag3PO4 nanocomposite for Malathion detection

Different nanomaterials in single (CeO2), binary (CdS/CeO2 and Ag3PO4/CeO2), ternary CdS/CeO2/Ag3PO4 (4:1 molar ratio) and conductive polymer supported (PANI-CdS/CeO2/Ag3PO4) were synthesized by co-precipitation method. Elemental analysis, crystal structure, surface area, morphology and optical properties of the as-synthesized nanoparticles were characterized. Electrochemical behavior of glassy carbon electrode modified by polyaniline supported CdS/CeO2/Ag3PO4 nanocomposite were also characterized by electrochemical impedance spectroscopy and cyclic voltammetry in 0.1 M of K3[Fe(CN)6] containing 0.1 M KCl at pH 7 with a frequency range of 0.1 to 1000 Hz, with an amplitude of 50 mV. The voltammogramm shows that the process of all as synthesized nanocomposites modified glassy carbon electrode is diffusion controlled. Under optimum conditions, the electrochemical sensor showed Malathion concentrations in linear range of 1-13 × 10−7 M, good reproducibility, and no interference by other pesticides and high recovery values around 98.90%. As-synthesized nanocomposite modified glassy carbon electrode exhibits the lowest detection limit of 3.0 × 10−9 M for Malathion detection. The simplicity of preparation, high sensitivity, good stability and reproducibility of this nanostructured polyaniline supported CdS/CeO2/Ag3PO4 electrode can be a potential candidate for application in the detection of Malathion.

Electrochemical Behavior of Glassy Carbon Electrode Modified by Layer-by-layer Self-assembly of Functional Graphene

In this paper, an electroactive polymer (PEI-Fc) was prepared by bonding ferrocene groups to the backbone of poly(ethyleneimine). On the other hand, sulfo-group modified graphene oxide (SGO) was also prepared. The multilayer film was constructed on glassy carbon electrode surface by the layer-by-layer adsorption method using PEI-Fc, SGO and PSS.The electorchemical activity of ferrocene in PEI-Fc/PSS or PEI-Fc/SGO film modified electrode was studied, especially the influence of layer number and pH. It is shown clearly that the graphene oxide(GO) has an inhibitory effect of electron transfer. Reduction of graphene oxide(RGO) increases the specific surface area of the glassy carbon electrode, and it is an ideal candidate for electrode modification. It is also found that ferrocene exhibited stronger electrochemical response in PEI-Fc/SGO film compared to the film without SGO. And the response of ferrocene increased with layer number and decrease of pH.

Electrochemical Investigation of Glucose Oxidation on a Glassy Carbon Electrode Using Voltammetric, Amperometric, and Digital Simulation Methods

AbstractIn this paper, we report the use of glassy carbon electrode for electrochemical oxidation of glucose in basic medium. The effect of glucose concentration, scan rate, and point potential was studied. Heterogeneous electron transfer parameters such as standard electron transfer rate constant (k0), transfer coefficient (α), and E0 were calculated using cyclic voltammetry (CV), semi integration of cyclic voltammetry (SICV), semi differentiation of cyclic voltammetry (SDCV), and digital simulation techniques. Amperometric experiments were performed for determination of glucose concentration in basic media. These experiments show a broad linear concentration range, up to 11 mM with a sensitivity of 927.96 μAmM−1cm−2. The lower detection limit (LOD) and Lower Quantification limit (LOQ) were found to be 50 μM and 0.5 mM, respectively. Effect of interfering species such as uric acid, ascorbic acid, acetaminophen, and chloride ion on the electrocatalytic behavior of glassy carbon electrode (GCE) was also studied.

Electrocatalytic behavior of glassy carbon electrode modified with ruthenium nanoparticles and ruthenium film

The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticles and ruthenium film was studied for electrochemical reduction of nicotinamide adenine dinucleotide (NAD+). The surface of GC electrode was modified via cathodic deposition of nanosized ruthenium at different potentials. Scanning electron microscopy (SEM) images showed two kinds of surface morphologies based on deposition potential: Ru nanoparticles-decorated GC at −0.3 V and Ru film-coated GC at −0.5 V versus Ag/AgCl. The electrochemical behavior of Ru nanoparticles and Ru film-modified GC electrodes in phosphate buffer solution containing NAD+ was investigated using voltammetric techniques. A prominent cathodic peak was observed on bare GC and Ru nanoparticles-modified GC at −1.2 V versus Ag/AgCl which was related to NAD+ reduction. The electrochemical response of Ru film electrode was reversible, exhibiting a reduction peak at ca. −1.0 V and an oxidation peak at ca. −0.55 V which was attributed mainly to the hydrogen evolution reaction. Electrochemical impedance analysis indicated lower charge transfer resistance of Ru film electrode for hydrogen evolution as compared to GC and Ru nanoparticle electrodes. Ru film-modified electrode was found less reactive than the nanoparticles-modified GC electrode for NAD+ reduction reaction due to hydrogen evolution reaction that proceeds exclusively on Ru film.

Electrochemical Simultaneous Detection of Dopamine, Ascorbic Acid and Uric Acid Using LaMnO3 Nanostructures

A facile hydrothermal approach was employed to prepare diverse morphologies of LaMnO3 nanostructures. These nanostructures were used to modify the electrode for electrochemical detection of dopamine (DA) in the presence of excess ascorbic acid (AA) and uric acid (UA). The morphology was tuned by changing the concentration of ethylene glycol (EG) and the size and roughness was controlled by urea. The electrochemical behavior of glassy carbon electrode (GCE) modified with different morphologies of prepared LaMnO3 nanostructures was investigated by using cyclic voltammetry (CV). The results confirm the LaMnO3 nanostructure prepared with 10 mL of EG has strong electrocatalytic activity than other concentrations of EG. This electrode was further used as an electroactive probe for the electrochemical simultaneous detection of DA, AA and UA. The final results clearly confirm the GCE modified with LaMnO3 nanostructure can be successfully employed for the electrochemical simultaneous detection of DA, AA and UA in real biological samples.

Altered Electrochemistry at Graphene- or Alumina-Modified Electrodes: Catalysis vs Electrocatalysis in Multistep Electrode Processes

The voltammetric behavior of glassy carbon electrodes modified with either submonolayer quantities of alumina or graphene is examined with respect to the two-electron, two-proton reaction of catechol (1,2-dihydroxybenzene) in aqueous solution. While the voltammetric behavior superficially hints at a change of electron transfer rate, an alternative explanation in terms of the changed thermodynamics of the intermediate species is advanced and rationalized.

Development of Silver Nanowires Based Highly Sensitive Amperometric Glucose Biosensor

AbstractThe fabrication of a highly sensitive amperometric glucose biosensor based on silver nanowires (AgNWs) is presented. The electrochemical behavior of glassy carbon electrode modified by Ag NWs exhibits remarkable catalytic performance towards hydrogen peroxide (H2O2) and glucose detection. The biosensor could detect glucose in the linear range from 0.005 mM to 10 mM, with a detection limit of 50 µM (S/N=3). The glucose biosensor shows high and reproducible sensitivity of 175.49 µA cm−2 mM and good stability. In addition, the biosensor exhibits a good anti‐interference ability and favorable stability over relatively long‐term storage (more than 21 days).

Electrochemical Sensor for Arabinose Based on Template‐free Pb/Cd Branched Nanorods on Glassy Carbon Electrode

AbstractIn this paper, the electrochemical behavior of glassy carbon electrodes modified with Cd/Pb (GC/Cd/Pb) branched nanorodes (NRs) was studied using cyclic voltammetry technique. The obtained results showed that the branched nanorods of Cd/Pb can be readily prepared without any templates. The modified electrode was characterized using scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDAX) and electrochemical impedance spectroscopy (EIS) techniques. The electrocatalytic behavior of GC/Cd/Pb electrode showed an increase in oxidation signal of arabinose by increasing its concentration. The catalytic current was linearly related to arabinose concentration in the range of 0.6 to 6.8 μM with a limit of detection 0.2 μM.

Electrocatalytic properties of glassy carbon electrodes modified with hydroxy derivatives of 9,10-anthraquinone for oxygen reduction reaction

The electrochemical and electrocatalytic behavior of glassy carbon electrodes modified by one mono and four dihydroxy derivatives of anthra-9,10-quinone compounds have been investigated by cyclic voltammetric technique. The stability of the modified electrodes was ascertained in acidic and neutral media. The surface morphology of modified electrode was characterized by scanning electron microscope. The influence of pH on the electrochemical and electrocatalytic behavior was studied and pH 6.0 or 7.0 was chosen as the optimum working pH by comparing the shift in oxygen reduction potential. The anthraquinone-adsorbed glassy carbon electrodes possess excellent electrocatalytic ability for oxygen reduction with overpotential ranging from 388 to 547 mV lower than that at a plain glassy carbon electrode. Hydrodynamic volatammetric studies were performed to determine the heterogeneous rate constants for the reduction of O2 at the surface of the modified electrodes, mass specific activity of the anthraquinones used, and the apparent diffusion coefficient of O2 in buffered aqueous O2-saturated solutions.

Electrocatalytic Behavior of Glassy Carbon Electrodes Modified with Multiwalled Carbon Nanotubes and Cobalt Phthalocyanine for Selective Analysis of Dopamine in Presence of Ascorbic Acid

AbstractThis work describes the development, electrochemical characterization and utilization of a cobalt phthalocyanine modified carbon nanotube electrode for the quantitative determination of dopamine in 0.2 mol L−1 phosphate buffer contaminated with high concentration of ascorbic acid. The electrode surface was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy which showed a modified surface presenting a charge transfer resistance of 500 Ω, against the 16.46 kΩ value found for the bare glassy carbon surface. A pseudo rate constant value of 5.4×10−4 cm s−1 for dopamine oxidation was calculated. Voltammetric experiments showed a shift of the peak potential of DA oxidation to less positive value at 390 mV as compared with that of a bare GC electrode at 570 mV. The electrochemical determination of dopamine, in presence of ascorbic acid in concentrations up to 0.1 mol L−1 by differential pulse voltammetry, yielded a detection limit as low as 2.56×10−7 mol L−1.

Electrocatalytic Reduction of Dioxygen on the Surface of Glassy Carbon Electrodes Modified with Cobalt Porphyrin Complexes

AbstractThe preparation and electrocatalytic behavior of glassy carbon electrodes modified with three different cobalt porphyrin complexes were investigated. The electrocatalytic ability of the modified electrodes for the reduction of dioxygen to hydrogen peroxide and water in air‐saturated aqueous solutions was examined by cyclic voltammetry and chronoamperometry techniques. The porphyrin‐adsorbed glassy carbon electrodes possess excellent electrocatalytic abilities for dioxygen reduction with overpotential about 0.5 V lower than that at a plain glassy carbon electrode. The experimental parameters were optimized and the mechanism of the catalytic process was discussed. The possible effects of the electron‐donating properties of groups in the meso‐position of the porphyrin ring were investigated.

Electrochemical behavior of glassy carbon electrodes modified by multi-walled carbon nanotube/surfactant films in a buffer solution and an ionic liquid

The electrochemical behavior of glassy carbon (GC) electrodes coated with multi-walled carbon nanotube (MWCNT)/surfactant films was studied in an ionic liquid and a phosphate buffer solution (pH = 6.86), using cyclic voltammetry. The dispersion of MWCNTs in different media was investigated by scanning and transmission electron microscopy. Cast films of MWCNT/zwitterionic dodecyldimethylamine oxide on a GC electrode show a typical redox couple in phosphate buffer solution, which is better than that of MWCNT/anionic sodium dodecyl sulfate and cationic alkyltrimethylammonium bromide. However in the ionic liquid, 1- n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]), the GC electrode modified by MWCNT/cationic surfactant films shows a well-defined irreversible reduction of MWCNTs. The cyclic voltammograms clearly show that the surfactant hydrophilic group plays an important role in the electrochemical behavior of the MWCNTs. The electrolytes also have an important effect. In an ionic liquid, the strong binding of the ionic liquid cations with the MWCNTs may change the structure of the modified films and lead to changes of electrochemical behavior.

Electrochemical behavior of glassy carbon electrodes modified by electrochemical oxidation

Glassy carbon electrodes were modified electrochemically by pretreatment in sulfate, phosphate or carbonate solutions by means of cycling the potential well into the positive limit of the solvent. Electrodes treated in this manner were then used to incorporate and concentrate a variety of redox species that were either cations or aromatic containing compounds, including Ru(bpy) 2+ 3, Ru(NH 3) 3+ 6, Cu(NH 3) 2+ 4, ferrocene, methylviologen, 1,4-benzoquinone, anthraquinone-2-sulfonate, riboflavin, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Surface-equivalent concentrations ranged from 5 × 10 −9 to 1 × 10 −7 mol cm −2 for electrodes pretreated for 10 min in sulfuric acid. An E 1/2 vs. pH study of 1,4-benzoquinone, riboflavin, FMN and FAD in modified electrodes shows that the p K a values shift toward higher pH (nearly 2 pH units). Results concerning the incorporation of redox compounds detected only by mediation with other electroactive complexes and the study of the modified electrodes in electrocatalysis are also discussed.