Composite Film-modified Glassy Carbon Electrode Research Articles

Electrochemical synthesis of graphene/polypyrrole nanotube composites for multifunctional applications

A conducting composite film has been fabricated using graphene oxide (GO) and pre-prepared one-dimensional polypyrrole (PPy) nanotube as the feedstock. GO with various oxygen-containing groups effectively promotes the dispersion of well-defined PPy nanotubes to obtain a stable and homogeneous GO/PPy complex solution. By a one-step and large-scale electrochemical reduction, the graphene/PPy nanotube composite film is successfully synthesized. Graphene nanosheets uniformly cover the surface of the electrode and PPy nanotubes act as spacers and conducting bridges to prevent the restacking of graphene sheets and connect the isolated graphene nanosheets. Electrochemical experiments indicate that the composite films have high performances due to the combination of the advantages of graphene and PPy nanotube. When the graphene/PPy nanotube composite is directly used as the supercapacitor electrode, it shows high specific capacitance and good cycling stability during 1000 charge/discharge cycles. Furthermore, an electrochemical biosensor is constructed through the entrapment of horseradish peroxidase (HRP) onto the composite film-modified glassy carbon electrode (GCE). The immobilized HRP showed high catalytic activity for the reduction of H2O2, which may be ascribed to high conductivity, great surface coverage, and good biocompatibility of the prepared graphene/PPy nanotube composite film. This method may be extended to prepare other conducting composite films with structure-controllable nanostructures in large scale for the application of electrochemical fields.

Electrochemical determination of methyl parathion using poly(malachite green)/graphene nanosheets–nafion composite film-modified glassy carbon electrode

A novel poly(malachite green)/graphene nanosheets–nafion (PMG/GNs–NF) composite film-modified glassy carbon electrode was developed to indirectly detect methyl parathion (MP). p-nitrophenol, the alkaline hydrolysis product of MP, was successfully determined at a relatively lower potential using this modified electrode due to the excellent electrocatalytic activity of PMG/GNs–NF composite film. The presence of GNs in the composite film enhanced the stability of PMG and increased the electron transfer rate. The kinetic parameters of modified electrodes were studied. What is more, the optimum experimental parameters affecting response were selected in terms of pH, accumulation potential, accumulation time, scanning cycles during polymerization of malachite green, and alkaline hydrolysis conditions. Under optimum conditions, the chronoamperometric response current was proportional to MP concentration over the range from 0.02 to 1.5 μM with a low-detection limit of 2.0 nM. Finally, the sensor was applied for the determination of MP in real samples, and the results were satisfactory with recoveries from 97.20 to 104.53 %. Due to its simple preparation, good reproducibility, and stability, this developed modified electrode provides a new platform for the detection of organophosphate pesticides.

Direct electrochemistry and electrocatalytic behavior of hemoglobin entrapped in chitosan/gold colloid/3-aminopropyl triethylene silane/Prussian blue composite film

Direct electrochemistry of hemoglobin (Hb) is achieved by immobilizing Hb–chitosan on a gold colloid/3-aminopropyl triethylene silane/Prussian blue composite film-modified glassy carbon electrode. The modified electrode exhibits a pair of well defined and quasi-reversible peaks with a formal potential of 0.205V. The immobilized Hb retains its biological activity and shows high catalytic activity to the reduction of hydrogen peroxide. Experimental conditions influencing the biosensor performances such as pH and potential are optimized and assessed. Under the optimized conditions, the catalytic currents are linear to the concentrations of H2O2 in the ranges of 2–480μM. The detection limit is 0.1μM (S/N=3). The electrochemical sensor has high stability and good reproducibility. Ultraviolet visible absorption spectra and Fourier transform infrared spectroscopy show that Hb keeps almost natural structure in the composite film. Therefore, the composite film is an alternative matrix for protein immobilization and biosensor preparation.

Sensitive detection of esculetin based on a CdSe nanoparticles-decorated poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite film

An electrochemical sensor based on a CdSe nanoparticles (NPs)-decorated poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (CdSe-PDDA-G) nanocomposite was fabricated for the sensitive detection of esculetin. The nanocomposite was characterized by X-ray diffraction (XRD), ultraviolet/visible spectra (UV-vis) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate the electrochemical behaviors of esculetin on the CdSe-PDDA-G composite film-modified glassy carbon electrode (GCE). The experimental results indicated that the incorporation of CdSe NPs with PDDA-G greatly enhanced the electrochemical response of esculetin. This electrochemical sensor displayed satisfactory analytical performance for esculetin detection over a range from 1.0 × 10(-8) to 5.0 × 10(-5) mol L(-1) with a detection limit of 4.0 × 10(-9) mol L(-1) (S/N = 3). Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of esculetin in real samples with satisfactory results.

Fabrication of poly(orthanilic acid)–multiwalled carbon nanotubes composite film-modified glassy carbon electrode and its use for the simultaneous determination of uric acid and dopamine in the presence of ascorbic acid

A multiwalled carbon nanotubes (MWNT) modified glassy carbon electrode (GCE) coated with poly(orthanilic acid) (PABS) film (PABS–MWNT/GCE) has been fabricated and used for simultaneous determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) by differential pulse voltammetry (DPV). Scanning electron microscopy, Fourier transform infrared spectra, and electrochemical techniques have been used to characterize the surface morphology of the PABS–MWNT composite film and the polymerization of ABS on electrode surface. In comparison with the bare GCE and the MWNT-modified GCE, the PABS–MWNT composite film-modified GCE, which combines the advantages of MWNT and the self-doped PABS, exhibits good selectivity and sensitivity for the simultaneous and selective determination of UA and DA in the presence of AA. Due to the different electrochemical responses of AA, DA, and UA, PABS–MWNT/GCE can resolve the overlapped oxidation peak of DA and UA into two well-defined voltammetric peaks with enhanced current responses using both cyclic voltammetry (CV) and DPV. The peak potential separations between DA and UA are 170 mV using CV and 160 mV using DPV, respectively, which are large enough for the selective and simultaneous determination of these species. In the presence of 0.5 mM AA, the DPV peak currents are linearly dependent on the concentration of UA and DA in the range of 6–55 and 9–48 μM with correlation coefficients of 0.997 and 0.993, respectively. The detection limits (S/N = 3) for detecting UA and DA are 0.44 and 0.21 μM, respectively. The PABS–MWNT/GCE shows good reproducibility and stability and has been used for the simultaneous determination of DA and UA in the presence of AA in samples with satisfactory results.

A new electrochemiluminescent sensing interface for clonazepam based on titanate nanotubes self-assembled film

A nanometer-sized titanic substance, titanate nanotube, was synthesized and used for investigating the electrochemiluminescence (ECL) behaviors of lucigenin. A self-assembled film of titanate nanotube was formed on the chitosan modified glassy carbon electrode (GCE) through electrostatic attraction. Comparing with the bare GCE, a dramatically enhanced (more than 50-fold) and more stable ECL emission of lucigenin could be achieved on the proposed TNTs/chitosan composite film-modified GCE under the cathodic potential scanning mode. Clonazepam was firstly found and employed as the coreactant to enhance ECL of lucigenin. Herein, this coreactant ECL system was investigated on the proposed ECL platform in detail. Under the optimum conditions, the proposed ECL sensor exhibited a linear response range of 1.0 × 10 −8–1.0 × 10 −4 M with detection limit of 8.4 × 10 −9 M and long-term stability for clonazepam. The possible mechanism for this sensor was also discussed.

Electrochemical properties of colchicine on the PoPD/SWNTs composite-modified glassy carbon electrode

Abstract A poly(o-phenylenediamine)/single-wall carbon nanotubes-modified electrode was prepared by electropolymerization on glassy carbon electrode. The morphology of the resulting PoPD/SWNTs composite was characterized by transmission electron microscopy (TEM) and the electrochemical properties of the modified electrode were characterized by cyclic voltammetry and ac impedance. The nanoporous composite film-modified glassy carbon electrode exhibits enhanced electrocatalytic behavior and good stability for the detection of colchicine. The large current response of colchicine on PoPD/SWNTs composite-modified electrode is probably caused by the synergistic effect of the electrocatalytic property of PoPD and SWNTs. The oxidative peak current increased linearly with the concentration of colchicine in the range of 1.0 × 10−7 to 1.0 × 10−5 mol l−1 by differential pulse voltammetry. The detection limit was 3.5 × 10−8 mol l−1. The proposed modified electrode provides a new promising and alternative way to detect colchicine.

Electrochemical determination diethylstilbestrol by a single-walled carbon nanotube/platinum nanoparticle composite film electrode

Platinum nanoparticles (Ptnano) were prepared and used in combination with single-wall carbon nanotube (SWNT) for fabricating electrochemical sensors with remarkably improved sensitivity toward diethylstilbestrol (DES). The glassy carbon (GC) electrode modified with SWNT/Ptnano composite film exhibited excellent electrochemical behaviors toward the redox of DES. Compared with the bare GC electrode and SWNTs film modified GC electrode, the redox peak currents at the SWNTs/Ptnano composite film modified GC electrode was enhanced greatly. The experimental parameters, which influence the peak current of DES, were optimized. Under optimal conditions, a linear response of DES was obtained in the range from 1.0 × 10−7 to 2.0 × 10−5 mol L−1 (R = 0.997) and with a limit of detect (LOD) of 1.5 × 10−8 mol L−1. The proposed procedure was successfully applied to determine the active ingredient in the DES tablet with satisfactory results.

Electrochemical methods for simultaneous determination of dopamine and ascorbic acid using cetylpyridine bromide/chitosan composite film-modified glassy carbon electrode

Abstract In this work, cetylpyridine bromide (CPB)/chitosan composite film-modified glassy carbon electrode (GCE) is developed for simultaneous determination of dopamine (DA) and ascorbic acid (AA) by differential pulse voltammetry (DPV). At CPB/chitosan composite film-modified GCE, the oxidation peak potential of AA shifts toward less positive potential and the peak current of AA increases greatly, while the oxidation peak potential of DA shifts toward more positive potential and peak current decreases greatly in comparison with that on bare electrode. Therefore, the common overlapped oxidation peaks of AA and DA can be separated completely by using CPB/chitosan composite film-modified electrode. For AA and DA in mixture, one can well separates from the other with potential difference of about 0.3 V, which is large enough to allow determination of one in the presence of the other. Under the optimum conditions, the anodic peak currents ( I pa ) of DPV are proportional to the concentration of AA in the range of 1.0 × 10 −5 to 2.0 × 10 −3 M, and to that of DA in the range of 4.0 × 10 −5 to 5.0 × 10 −3 M.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in Nafion-RTIL composite film

The composite film based on Nafion and hydrophobic room-temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim] PF 6) was explored. Here, Nafion was used as a binder to form Nafion-ionic liquids composite film and help [bmim] PF 6 effectively adhered on glassy carbon (GC) electrode. X-ray photoelectron spectroscopy (XPS), cyclic voltammtery (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize this composite film, showing that the composite film can effectively adhere on the GC electrode surface through Nafion interacting with [bmim] PF 6 and GC electrode. Meanwhile, doping [bmim] PF 6 in Nafion can also effectively reduce the electron transfer resistance of Nafion. The composite film can be readily used as an immobilization matrix to entrap horseradish peroxidase (HRP). A pair of well-defined redox peaks of HRP was obtained at the HRP/Nafion-[bmim] PF 6 composite film-modified GC electrode through direct electron transfer between the protein and the underlying electrode. HRP can still retain its biological activity and enhance electrochemical reduction towards O 2 and H 2O 2. It is expected that this composite film may find more potential applications in biosensors and biocatalysis.