A new carbon composite electrode material, based on mixing glassy carbon (GC) microparticles with an organic pasting liquid is described. The resulting glassy carbon paste electrode (GCPE) combines the electrochemical properties of GC with the various advantages of composite electrodes. Glassy carbon pastes (GCPs) offer high electrochemical reactivity, a wide accessible potential window, a low background current, and are inexpensive, easy to prepare, modify, and renew. The new material has a lower double-layer capacitance and a higher heterogeneous rate constant (for ferricyanide) compared to conventional carbon pastes (CPs). Scanning electron microscopy (SEM) images indicate significant differences in the structure of GCPE and carbon paste electrode (CPE). Factors influencing the electrode kinetics of GCPE surfaces are discussed. The electrochemical properties and advantages of GCPE should be of broad utility in electroanalysis. 相似文献
The effect of various deposition techniques, electrode materials and posttreatment with tetrabutylammonium and tetrabutylphosphonium salts on the electrochemical behavior and stability of various Prussian blue (PB) modified electrodes, namely PB modified glassy carbon electrodes, silicate‐film supported PB modified glassy carbon electrodes, PB‐doped silicate glassy carbon electrodes, PB modified carbon ceramic electrodes using electrochemical deposition and PB modified carbon ceramic electrodes using chemical deposition is reported. Cyclic voltammetry and amperometric measurements of hydrogen peroxide were performed in a flow injection system while the carrier phosphate buffer (pH 7.0) with a flow rate of 0.8 mL min?1 was propelled into the electrochemical flow through cell housing the PB modified working electrode as well as an Ag|AgCl|0.1 M KCl reference and a Pt auxiliary electrode. The results showed that the deposition procedure, electrode material and posttreatment with additional chemicals can significantly alter the stability and electrochemical behavior of the PB film. Among the studied PB modified electrodes, those based on carbon ceramic electrodes modified with a film of electropolymerized PB showed the best electrochemical stability. 相似文献
A new carbon electrode material, obtained by mixing single wall carbon nanotubes (SWNTs) with a mineral oil binder is studied. Carbon nanotube pastes show the special properties of carbon nanotubes combined with the various advantages of composite electrodes such as a very low capacitance (background current) and the possibility of an easy preparation, modification and renewal. A better knowledge of the characteristics of electrode reactions at carbon nanotube paste (CNTP) electrodes was obtained studying the electron transfer rates of various redox couples under different pretreatment conditions. A critical comparison with carbon paste (CP), platinum (Pt) and glassy carbon (GC) electrodes was also carried out. Capacitance and resistance values were also calculated for all electrodes investigated. Both untreated and treated CNTP electrodes showed a low resistance while the capacitance was markedly reduced with CNTP electrodes previously treated with concentrated nitric acid. An electrochemical pretreatment on CNTP electrodes was developed which showed an excellent result towards two‐electron quinonic structure species. After this treatment the heterogeneous standard rate constants for p‐methylaminophenol sulfate (MAP) and dopamine resulted to be significantly higher (2.1×10?2 cm/s and 2.0×10?2 cm/s, respectively) than those obtained with the other electrodes studied. Reproducibility, stability and storage characteristics of CNTP electrodes were also reported. 相似文献
Wet poly(vinyl chloride) (wPVC) coated glassy carbon (GC) electrode was prepared by casting a DMF solution of poly(vinyl chloride) on glassy carbon and immersing it in methanol, and then in water. The wPVC coated GC (wPVC/GC) electrode showed electrochemical activity in aqueous solution; therefore, it was possible to obtain a wPVC/polypyrolle (PPy) composite by electropolymerization from aqueous solution of pyrolle (Py) into the wPVC matrix on the electrode. PPy segregated in wPVC matrix and the mechanical properties of PPy was improved by forming a composite without changing the electrochemical properties of PPy. The PPy/wPVC ratio can be controlled by controlling the concentration of PVC in DMF solution. 相似文献
Characterization and application of graphene sheets modified glassy carbon electrodes (graphene/GC) have been presented for the electrochemical bio-sensing. A probe molecule, potassium ferricyanide is employed to study the electrochemical response at the graphene/GC electrode, which shows better electron transfer than graphite modified (graphite/GC) and bare glassy carbon (GC) electrodes. Based on the highly enhanced electrochemical activity of NADH, alcohol dehydrogenase (ADH) is immobilized on the graphene modified electrode and displays a more desirable analytical performance in the detection of ethanol, compared with graphite/GC or GC based bio-electrodes. It also exhibits good performance of ethanol detection in the real samples. From the results of electrochemical investigation, graphene sheets with a favorable electrochemical activity could be an advanced carbon electrode materials for the design of electrochemical sensors and biosensors. 相似文献
This study introduces a new surface-renewable electrode based on a sol–gel derived graphene ceramic composite. The electrode was prepared by dispersing graphene nanosheets into a solution of the sol–gel precursors containing methyl triethoxysilane in methanol and hydrochloric acid. During hydrolysis of methyl triethoxysilane, the graphene nanosheets are trapped in the gel. After moulding and drying the composite, it can be used as a surface-renewable electrode to which we refer as a graphene ceramic composite electrode (GCCE). Cyclic voltammograms of the hexacyanoferrate(II/III) model redox system at the GCCE were compared to those obtained with a conventional carbon ceramic electrode and showed a highly improved electron transfer rate at the GCCE. The electrocatalytic oxidation of ascorbic acid as a model analyte was then studied at working potential of 50 mV and over the 3–84 μM concentration range. It revealed a sensitivity of 6.06 μA μM?1 cm?2 and a detection limit of 0.82 μM. The GCCE was successfully applied to the determination of ascorbic acid in orange juice and urine samples. Advantages such as good mechanical and chemical stability, ease of fabrication, and reproducible preparation make the GCCE a potentially useful and widely applicable renewable electrode for use in routine analysis. Fig. 1
(Left) FESEM image and photograph of the graphene ceramic composite electrode (GCCE); (right) the cyclic voltammogram of the renewable GCCE in 5 mM K3[Fe(CN)6] solution containing 0.1 M KNO3 at scan rate of 100 mV s?1相似文献
This letter describes the formation and possible electrochemical applications of molecular films of water-miscible imidazolium-based ionic liquids (ILs) on glassy carbon (GC) electrodes. X-ray photoelectron spectroscopy (XPS) and electrochemical results indicate that the water-miscible ILs used in this study can interact with the GC electrode and form molecular films on the electrode surface. The formed molecular films are found to possess striking electrochemical properties such as electrocatalysis toward ascorbic acid (AA) and the capability to facilitate direct electron transfer of horseradish peroxidase (HRP). This demonstration would pave the way for new electrochemical applications of water-miscible ILs and is envisaged to be useful for the investigation of the electrochemical properties of water-miscible ILs in aqueous media provided the same counteranion is used as the supporting electrolyte. 相似文献
Abstract Multiwalled carbon nanotubes (MWNTs) were treated with a mixture of concentrated sulfuric and nitric acid to introduce carboxylic acid groups to the nanotubes. Conducting polymer film was prepared by electrochemical polymerization of neutral red (NR). By using a layer‐by‐layer method, homogeneous and stable MWNTs and poly (neutral red) (PNR) multilayer films were alternately assembled on glassy carbon (GC) electrodes. With the introduction of PNR, the MWNTs/PNR multilayer film system showed synergy between the MWNTs and PNR, with a significant improvement of redox activity due to the excellent electron‐transfer ability of carbon nanotubes (CNTs) and PNR. The electropolymerization is advantageous, providing both prolonged long‐term stability and improved catalytic activity of the resulting modified electrodes. The MWNTs/PNR multilayer film modified glassy carbon electrode allows low potential detection of hydrogen peroxide with high sensitivity and fast response time. As compared to MWNTs and PNR‐modified GC electrodes, the magnitude of the amperometric response of the MWNTs/PNR composite‐modified GC electrode is more than three‐fold greater than that of the MWNTs modified GC electrode, and nine‐fold greater than that of the PNR‐modified GC electrode. With the immobilization of glucose oxidase onto the electrode surface using glutaric dialdehyde, a biosensor that responds sensitively to glucose has been constructed. In pH 6.98 phosphate buffer, nearly interference‐free determination of glucose has been realized at ?0.2 V vs. SCE with a linear range from 50 µM to 10 mM and response time <10s. The detection limit was 10 µM glucose (S/N=3). 相似文献
A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM?1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples. 相似文献
An electrochemical device was developed for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) using differential pulse voltammetry and glassy carbon (GC) electrodes modified with reduced graphene oxide (rGO) and silver nanoparticle (AgNP) composites, synthesised using both chemical and electrochemical methods. The morphology and electrochemical behaviour of the GC electrodes modified with the rGO/AgNP (chemical method) and rGO‐AgNP (electrochemical method) composites were characterised by scanning electron microscopy and cyclic voltammetry. These techniques demonstrated that, in both methods, the graphene oxide was modified by the AgNPs, and the composite synthesised by the electrochemical method showed a better dispersion of the nanoparticles, resulting in an increase in the surface area compared to the rGO/AgNP composite. The GC/rGO‐AgNP electrode was evaluated and optimised for the simultaneous determination of SMX and TMP, achieving detection limits of 0.6 μmol L−1 for the SMX and 0.4 μmol L−1 for the TMP. The proposed GC/rGO‐AgNP electrochemical device was successfully applied to the simultaneous determination of SMX and TMP in wastewaters samples. 相似文献
This study introduces a new surface-renewable electrode based on a sol–gel derived graphene ceramic composite. The electrode was prepared by dispersing graphene nanosheets into a solution of the sol–gel precursors containing methyl triethoxysilane in methanol and hydrochloric acid. During hydrolysis of methyl triethoxysilane, the graphene nanosheets are trapped in the gel. After moulding and drying the composite, it can be used as a surface-renewable electrode to which we refer as a graphene ceramic composite electrode (GCCE). Cyclic voltammograms of the hexacyanoferrate(II/III) model redox system at the GCCE were compared to those obtained with a conventional carbon ceramic electrode and showed a highly improved electron transfer rate at the GCCE. The electrocatalytic oxidation of ascorbic acid as a model analyte was then studied at working potential of 50 mV and over the 3–84 μM concentration range. It revealed a sensitivity of 6.06 μA μM−1 cm−2 and a detection limit of 0.82 μM. The GCCE was successfully applied to the determination of ascorbic acid in orange juice and urine samples. Advantages such as good mechanical and chemical stability, ease of fabrication, and reproducible preparation make the GCCE a potentially useful and widely applicable renewable electrode for use in routine analysis.
Applicability of square wave voltammetry for the determination of Cu(II) ions by PolyLut/GC and PolyKae/GC electrodes was evaluated in this study. For this luteolin and kaempferol were electrochemically polymerized on glassy carbon (GC) electrode surface in order to get polyluteolin and polykaempferol-modified glassy carbon electrodes (PolyLut/GC and PolyKae/GC, correspondingly). The formation of polyphenol layer on the GC electrode surface was evidenced by atomic force microscopy. Square wave voltammetry was found to be more sensitive in comparison with differential pulse voltammetry. It was determined that PolyLut/GC and PolyKae/GC electrodes offered great sensitivity towards Cu(II) ions with very low limit of detection, good reproducibility, sufficient stability and excellent selectivity of analytical signal. 相似文献
Poly(N-isopropylacrylamide)-modified graphene oxide (PNIPAm-GO), which is a type of thermally responsive GO, was designed and synthesized through a covalent “grafting-from” strategy. The as-prepared modified nanosheets integrated the individual advantages of two components, such as the thermal sensitivity of the PNIPAm terminal as well as the conductivity and the open 2D structure of the GO substrate. PNIPAm-GO was able to perform the reversible regulation of hydrophilicity/hydrophobicity in aqueous solution upon variations in the temperature. Such a unique property might also lead to the utilization of PNIPAm-GO as an intelligent electrode material to achieve a switchable electrochemical response toward a [Fe(CN)6]3−/4− probe. The PNIPAm-GO modified glassy carbon electrode (PNIPAm-GO/GC electrode) was able to exhibit better electrochemical performance in an ON/OFF switching effect than the PNIPAm-modified glassy carbon electrode (PNIPAm/GC electrode) without GO owing to the intrinsic properties and large surface area of the introduced GO. Moreover, it was found that the PNIPAm-GO/GC electrode also displayed excellent thermally responsive electrocatalysis toward the detection of 1,4-dihydro-β-nicotinamide adenine dinucleotide (NADH) and dopamine (DA), which resulted in two different catalytic statuses on the same electrode. This kind of switchable catalytic performance of the PNIPAm-GO/GC electrode might greatly enhance the flexibility of its application, and thus it is expected to have wide potential for applications in the fields of biosensors and biocatalysis. 相似文献