Electrochemistry and electrocatalytic activity of catechin film on a glassy carbon electrode toward the oxidation of hydrazine

A very stable electroactive film of catechin was electrochemically deposited on the surface of activated glassy carbon electrode. The electrochemical behavior of catechin modified glassy carbon electrode (CMGCE) was extensively studied using cyclic voltammetry. The properties of the electrodeposited films, during preparation under different conditions, and the stability of the deposited film were examined. The charge transfer coefficient (α) and charge transfer rate constant (k _s) for catechin deposited film were calculated. It was found that the modified electrode exhibited excellent electrocatalytic activity toward hydrazine oxidation and it also showed a very large decrease in the overpotential for the oxidation of hydrazine. The CMGCE was employed to study electrocatalytic oxidation of hydrazine using cyclic voltammetry, rotating disk voltammetry, chronoamperometry, amperometry and square-wave voltammetry as diagnostic techniques. The catalytic rate constant of the modified electrode for the oxidation of hydrazine was determined by cyclic voltammetry, chronoamperometry and rotating disk voltammetry and was found to be around 10⁻³ cm s⁻¹ . In the used different voltammetric methods, the plot of the electrocatalytic current versus hydrazine concentration is constituted of two linear segments with different ranges of hydrazine concentration. Furthermore, amperometry in stirred solution exhibits a detection limit of 0.165 μM and the precision of 4.7% for replicate measurements of 40.0 μM solution of hydrazine.     

Electrocatalytic Oxidation of Hydrogen Peroxide at a Sol‐gel Derived Carbon Ceramic Electrode Modified with Copper Iodide

A novel modified carbon ceramic electrode using CuI as modifier was fabricated. The copper iodide modified sol‐gel derived carbon ceramic (CIM‐SGD‐CC) electrode has high catalytic ability for electrooxidation of hydrogen peroxide. The charge transfer coefficient (α) and exchange current density (j₀) for the modified electrode were calculated. It has been shown that using the CIM‐SGD‐CC electrode, hydrogen peroxide can be determined by cyclic voltammetry and amperometry with limit of detections 26 and 0.31 μmol L^?1, respectively. The advantages of the modified CCE are its good stability and reproducibility of surface renewal by simple polishing, excellent catalytic activity.     

Adsorptive Stripping Differential Pulse Voltammetric Determination of Risperidone with a Multi‐Walled Carbon Nanotube‐Ionic Liquid Paste Modified Glassy Carbon Electrode

A new composite electrode has been fabricated based on coating multi‐walled carbon nanotubes (MWCNTs) and n‐octylpyridinum hexafluorophosphate (OPPF₆) ionic liquid composite on a glassy carbon (GC) electrode (OPPF₆‐MWCNTs/GCE). This electrode shows very attractive electrochemical performances for electrooxidation of risperidone (RIS) compared to conventional electrodes using carbon and mineral oil, notably improved sensitivity and stability. The oxidation peak potentials in cyclic voltammogram of RIS on the OPPF₆‐MWCNTs/GCE was occurred around 230 mV vs. SCE at Britton–Robinson (B–R) buffer (pH 4.0) at scan rate of 100 mV s^?1. The electrochemical parameters such as diffusion coefficient (D), charge transfer coefficient (α) and the electron transfer rate constant (k/_s) were determined using cyclic voltammetry. Under the optimized conditions, the peak current was linear to risperidone concentration over the concentration range of 10–200 nM with sensitivity of 0.016 μA/nM^?1 using differential pulse voltammetry. The detection limit was 6.54 nM (S/N = 3). The electrode also displayed good selectivity and repeatability. In the presence of clozapine (CLZ) the response of RIS kept almost unchanged. Thus this electrode could find application in the determination of RIS in some real samples. The analytical performance of the OPPF₆‐MWCNTs/GCE was demonstrated for the determination of RIS in human serum and pharmaceutical samples.     

Nanostructured Base Electrochemical Sensor for Simultaneous Quantification and Voltammetric Studies of Levodopa and Carbidopa in Pharmaceutical Products and Biological Samples

A novel carbon paste electrode modified with carbon nanotubes and 5‐amino‐2′‐ethyl‐biphenyl‐2‐ol (5AEB) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for electrocatalytic oxidation of levodopa (LD) and carbidopa (CD), is described. Cyclic voltammetry (CV) was used to investigate the redox properties of this modified electrode at various scan rates. The apparent charge transfer rate constant, k_s, and transfer coefficient, a, for electron transfer between 5AEB and CPE were calculated as 17.3 s^?1 and 0.5, respectively. Square wave voltammetry (SWV) exhibits a linear dynamic range from 2.5×10^?7 to 2.0×10^?4 M and a detection limit of 9.0×10^?8 M for LD.     

Preparation and Electrochemical Characterization of an Enzyme Electrode Based on Catalase Immobilized onto a Multiwall Carbon Nanotube‐Thionine Film

The present study was aimed at investigating the use of a mixture multiwall carbon nanotube (MWCNT) and thionine (Th) dye in designing of a thionine‐based electrochemical biosensor containing catalase (Ct) enzyme (MWCNT‐Nafion‐Th/Ct) onto a glassy carbon electrode (GCE). The effects of pH, MWCNT concentration and thionine concentration on electrochemical response were explored for optimum analytical performance. The modified electrode exhibited a pair of well‐defined, quasi‐reversible peaks at formal potential (E^o′) = ‐0.218 ± 0.017 V vs. Ag/AgCl corresponding to the Th_ox/Th_red redox couples in the presence of MWCNT, Nafion, and Ct. The electrochemical parameters, including charge‐transfer coefficient (0.36), and apparent heterogeneous electron transfer rate constant (4.28 ± 0.26 s^?1) were determined. Using differential pulse voltammetry, the prepared enzyme electrode exhibited a linear response to hydrogen peroxide (H₂O₂) in the range of 10.0‐100.0 μM with a detection limit 8.7 μM and a sensitivity of 6051.0 μA mM^?1 cm^?2.     

Nanomolar determination of hydrazine by TiO2 nanoparticles modified carbon paste electrode

In the present paper, the use of a novel carbon paste electrode modified by N,N′(2,3-dihydroxybenzylidene)-1,4-phenylene diamine (DHBPD) and TiO₂ nanoparticles prepared by a simple and rapid method for the determination of hydrazine (HZ) was described. In the first part of the work, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. A linear segment was found with a slope value of about 48 mV/pH in the pH range 2.0–12.0. The apparent charge transfer rate constant (k _s) and transfer coefficient (α) for electron transfer between DHBPD and TiO₂ nanoparticles-modified carbon paste electrode were calculated. In the second part of the work, the mediated oxidation of HZ at the modified electrode was described. It has been found that under optimum condition (pH 8.0) in cyclic voltammetry, a high decrease in overpotential occurs for oxidation of HZ at the modified electrode. The values of electron transfer coefficients (α) and diffusion coefficient (D) were calculated for HZ, using electrochemical approaches. Differential pulse voltammetry exhibited a linear dynamic range from 1.0 × 10⁻⁸ to 4.0 × 10⁻⁶ M and a detection limit (3σ) of 9.15 nM for HZ. Finally, this method was used for the determination of HZ in water samples, using standard addition method.     

Sensitive voltammetric determination of rutin at a carbon nanotubes-ionic liquid composite electrode

A new composite electrode of multiwall carbon nanotubes (MWNTs) and 1-dodecyl-3-methylimidazolium hexafluorophosphate (DDMIMPF₆) was fabricated to determine rutin. This electrode showed very attractive electrochemical performances compared to other kinds of ionic liquid modified electrodes and notably improved sensitivity and stability. Electrochemical behavior of rutin at the composite electrode had been investigated in pH 2.09 Britton–Robinson buffer solution by cyclic voltammetry and square wave voltammetry. The experimental results suggested that the composite electrode exhibited an electrocatalytic activity toward the redox of rutin. The electrochemical parameters of rutin were calculated with the results of the charge transfer coefficient (α) and the standard rate constant (k _s) as 0.48 and 2.09 s^?1. Under the selected conditions, the reduction peak current was linearly dependent on the concentration of rutin in the range of 0.03–1.5 μM, with a detection limit of 0.01 μM (S/N?=?3). The relative standard deviation for six times successive determination of 1 μM rutin was 1.6 %. The method was successfully applied to the determination of rutin in tablets and urine samples without the influence of the coexisting substances. In addition, the MWNTs/DDMIMPF₆ composite electrode exhibits a distinct advantage of simple preparation, surface renewal, good reproducibility, and stability.     

Modified Graphite Paste Electrode with Lewatit FO36 Nanoresin/Multi-Walled Carbon Nanotubes for Determination of Quercetin

In the present study, the electrochemical oxidation of quercetin (QUR) was investigated using a graphite paste electrode (GPE) modified with multi-walled carbon nanotube and Lewatit FO36 nanoresin (LFONR-MWCNT/GPE). LFONR-MWCNT/GPE could effectively a sensitive anodic peak at around 0.23 V (vs. SCE) in a 0.10 M phosphate buffer solution. Modified electrode revealed that activated with multiwalled carbon nanotube and LFONR was capable of facilitating electron transfer and increasing surface area. The electrochemical oxidation of QUR was studied using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Some kinetic parameters for electrochemical oxidation of QUR including total number of electrons (n) and standard heterogeneous rate constant (k_s) were also determined. The calibration graph consisted of two linear segments of 1.8–25.0 μM, and 25.0–570.0 μM with a detection limit of 0.213 μM (based on 3S_b). The applicability of the method to juice of peach, red grape, sour cherry and Gincora tablets analysis was also evaluated.     

OH functionalized Multi-Walled Carbon Nanotube modified electrode as electrochemical sensor for the detection of Aceclofenac

ABSTRACT

The rapid electrochemical determination of Aceclofenac (ACF) has been employed by cyclic voltammetry (CV), differential pulse voltammetry (DPV) using developed OH-functionalised multiwalled carbon nanotube carbon paste electrode (OH-MWCNT/CPE). Modified electrode was characterised by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction spectroscopy (XRD), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The ACF exhibits two oxidation peaks at +0.4 V, +0.66 V and one reduction peak at +0.3 V. The active surface area of the bare carbon paste electrode (BCPE) and modified electrode have been characterised by using K₃[Fe(CN)₆] solution containing 0.1 M KCl. In DPV mode, variation of ACF gave the limit of detection (LOD = 3s/m) 0.246 μM over the concentration range 1.0 to 190.0 μM (R² = 0.9994). The developed electrode has good stability, reproducibility and could be successfully validated for the detection of ACF in pharmaceutical samples and biological fluids.     

Preparation,Characterization, and Bioelectrocatalytic Properties of Hemoglobin Incorporated Multiwalled Carbon Nanotubes‐Poly‐L‐lysine Composite Film Modified Electrodes Towards Bromate

The present work describes preparation of hemoglobin‐incorporated multiwalled carbon nanotubes‐poly‐L ‐lysine (MWCNT‐PLL)/Hb) composite modified electrode film modified glassy carbon electrode (GCE) and its electrocatalytic behavior towards reduction of bromate ( ) in 0.1 M acetate buffer (pH 5.6). The modified electrode has been successfully fabricated by immobilizing hemoglobin on MWCNT dispersed in poly‐L ‐lysine. The surface morphologies of MWCNT, PLL and Hb were characterized using atomic force microscopy (AFM). The voltammetric features suggested that the charge transport through the film was fast and the electrochemical behavior resembles that of surface‐confined redox species. Cyclic voltammetry was used to investigate the electrocatalytic behavior of the modified electrode towards bromate and was compared with that of the CNT‐modified as well as bare electrode. The analytical determination of bromate has been carried out in stirred solution at an optimized potential with a sensitivity of 7.56 μA mM^?1 and the calibration curve was linear between 1.5×0^?5 to 6.0×0^?3 M.     

Immobilization of [Cu(bpy)2]Br2 complex onto a glassy carbon electrode modified with α-SiMo12O40 and single walled carbon nanotubes: Application to nanomolar detection of hydrogen peroxide and bromate

A simple procedure has been used for preparation of modified glassy carbon electrode with carbon nanotubes and copper complex. Copper complex [Cu(bpy)₂]Br₂ was immobilized onto glassy carbon (GC) electrode modified with silicomolybdate, α-SiMo₁₂O₄₀⁴⁻ and single walled carbon nanotubes (SWCNTs)_. Copper complex and silicomolybdate irreversibly and strongly adsorbed onto GC electrode modified with CNTs. Electrostatic interactions between polyoxometalates (POMs) anions and Cu-complex, cations mentioned as an effective method for fabrication of three-dimensional structures. The modified electrode shows three reversible redox couples for polyoxometalate and one redox couple for Cu-complex at wide range of pH values. The electrochemical behavior, stability and electron transfer kinetics of the adsorbed redox couples were investigated using cyclic voltammetry. Due to electrostatic interaction, copper complex immobilized onto GC/CNTs/α-SiMo₁₂O₄₀⁴⁻ electrode shows more stable voltammetric response compared to GC/CNTs/Cu-complex modified electrode. In comparison to GC/CNTs/Cu-complex the GC/CNTs/α-SiMo₁₂O₄₀⁴⁻ modified electrodes shows excellent electrocatalytic activity toward reduction H₂O₂ and BrO₃⁻ at more reduced overpotential. The catalytic rate constants for catalytic reduction hydrogen peroxide and bromate were 4.5(±0.2) × 10³ M⁻¹ s⁻¹ and 3.0(±0.10) × 10³ M⁻¹ s⁻¹, respectively. The hydrodynamic amperommetry technique at 0.08 V was used for detection of nanomolar concentration of hydrogen peroxide and bromate. Detection limit, sensitivity and linear concentration range proposed sensor for bromate and hydrogen peroxide detection were 1.1 nM and 6.7 nA nM⁻¹, 10 nM-20 μM, 1 nM, 5.5 nA nM⁻¹ and 10 nM-18 μM, respectively.     

Graphene Functionalized Graphite Electrode with Diphenylacetylene for Sensitive Electrochemical Determination of Adenosine‐5′‐triphosphate

In this paper a molecular wire modified carbon paste electrode (MW‐CPE) was firstly prepared by mixing graphite powder with diphenylacetylene (DPA). Then a graphene (GR) and chitosan (CTS) composite film was further modified on the surface of MW‐CPE to receive the graphene functionalized electrode (CTS‐GR/MW‐CPE), which was used for the sensitive electrochemical detection of adenosine‐5′‐triphosphate (ATP). The CTS‐GR/MW‐CPE exhibited excellent electrochemical performance and the electrochemical behavior of ATP on the CTS‐GR/MW‐CPE was carefully studied by cyclic voltammetry with an irreversible oxidation peak appearing at 1.369 V (vs. SCE). The electrochemical parameters such as charge transfer coefficient (α) and electrode reaction standard rate constant (k_s) were calculated with the results of 0.53 and 5.28×10^?6 s^?1, respectively. By using differential pulse voltammetry (DPV) as detection technique, the oxidation peak current showed good linear relationship with ATP concentration in the range from 1.0 nM to 700.0 µM with a detection limit of 0.342 nM (3σ). The common coexisting substances, such as uric acid, ascorbic acid and guanosine‐5′‐triphosphate (GTP), showed no interferences and the modified electrode was successfully applied to injection sample detection.     

Adsorption and Reactivity of Chlorogenic Acid at a Hydrophobic Carbon Ceramic Composite Electrode: Application for the Amperometric Detection of Hydrazine

Sol-gel technique was used for construction of a carbon composite electrode. The prepared carbon ceramic electrode was modified with electroless deposition of chlorogenic acid for less than 1 min. The adsorbed thin films of chlorogenic acid on carbon composite electrode show one pair of peaks with a surface confined characteristic, which strongly depends on the solution pH, as anticipated for quinone /hydroquinone functionalities. The modified electrode shows highly catalytic activity toward hydrazine electrooxidation at wide pH range (5–11). Also the rotating modified electrode shows excellent analytical performance for amperometric determination of hydrazine. The detection limit, sensitivity, response time and linear dynamic range are 20 nM, 220 nA / μM, 1 second and 0.1 μM-1 mM, respectively. The catalytic rate constant for hydrazine oxidation at the surface of modified electrode was evaluated by cyclic voltammetry and was found to be around 1.5×10³ M⁻¹s⁻¹in phosphate buffer solution (pH 8). The precision of chronoamperometric measurements was 1–3% for 5 replicate determinations in the concentration range of the linear calibration. The reproducibility of modified CCE was evaluated with 8 successive polishing and modifications and then the anodic peak current was measured (RSD 2%). The advantages of this sensor are excellent catalytic activity, high sensitivity, good reproducibility and simplicity of preparation at short time periods.     

A study of the electrochemical behavior of an oxadiazole derivative electrodeposited on multi-wall carbon nanotube-modified electrode and its application as a hydrazine sensor

In this study, an oxadiazole multi-wall carbon nanotube-modified glassy carbon electrode (OMWCNT−GCE) was used as a highly sensitive electrochemical sensor for hydrazine determination. The surface charge transfer rate constant, k _s, and the charge transfer coefficient, α, for electron transfer between GCE and electrodeposited oxadiazole were calculated as 19.4 ± 0.5 s⁻¹ and 0.51, respectively at pH = 7.0. The obtained results indicate that hydrazine peak potential at OMWCNT−GCE shifted for 14, 109, and 136 mV to negative values as compared with oxadiazole-modified GCE, MWCNT−GCE, and activated GCE surface, respectively. The electron transfer coefficient, α, and the heterogeneous rate constant, k′, for the oxidation of hydrazine at OMWCNT−GCE were also determined by cyclic voltammetry measurements. Two linear dynamic ranges of 0.6 to 10.0 μM and 10.0 to 400.0 μM and detection limit of 0.17 μM for hydrazine determination were evaluated using differential pulse voltammetry. In addition, OMWCNT−GCE was shown to be successfully applied to determine hydrazine in various water samples.

     

Electrocatalytic Determination of Ascorbic Acid at the Surface of 2,7‐Bis(ferrocenyl ethyl)fluoren‐9‐one Modified Carbon Paste Electrode

A chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10^?5 cm² s^?1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10^?5 M–2.0×10^?3 M and 3.1×10^?5 M–3.3×10^?3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10^?5 M and 9.0×10^?6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations.     

High-sensitive amperometric hydrazine sensor based on chemically synthesized zinc nitroprusside nanoparticle-supported carbon ceramic electrode

Zinc nitroprusside (ZnNP) nanoparticles were fabricated at the surface of zinc powder-doped carbon ceramic electrode (CCE) by a chemical derivatization process. This modified electrode was characterized by scanning electron microscopy, atomic force microscopy and cyclic voltammetry techniques. The charge transfer rate constant (k _s) and charge transfer coefficient (α) were calculated for the electron exchange reaction of the ZnNP thin film. The ZnNP nanoparticle-modified CCE (ZnNP|CCE) showed good electrocatalytic activity toward hydrazine oxidation. The limit of detection (S/N = 3) and sensitivity were found to be 0.16 µM and 0.21 µA/µM, respectively. The mechanism of hydrazine electrooxidation at the electrode surface was studied. Finally, the ZnNP|CCE was successfully used for the determination of trace amount of hydrazine in different spiked and real samples.     

Amperometric sulfite sensor based on multiwalled carbon nanotubes/ferrocene-branched chitosan composites

A novel amperometric sensor for the determination of sulfite was fabricated based on multiwalled carbon nanotubes (MWCNTs)/ferrocene-branched chitosan (CHIT-Fc) composites-covered glassy carbon electrode (GCE). The electrochemical behavior of the sensor was investigated in detail by cyclic voltammetry. The apparent surface electron transfer rate constant (K_s) and charge transfer coefficient (α) of the CHIT-Fc/MWCNTs/GCE were also determined by cyclic voltammetry, which were about 1.93 cm s⁻¹ and 0.42, respectively. The sensor displayed good electrocatalytic activity towards the oxidation of sulfite. The peak potential for the oxidation of sulfite was lowered by at least 330 mV compared with that obtained at CHIT/MWCNTs/GCE. In optimal conditions, linear range spans the concentration of sulfite from 5 μM to 1.5 mM and the detection limit was 2.8 μM at a signal-to-noise ratio of 3. The proposed method was used for the determination of sulfite in boiler water. In addition, the sensor has good stability and reproducibility.     

Fabrication of Glucose Biosensor Based on Encapsulation of Glucose‐Oxidase on Sol‐Gel Composite at the Surface of Glassy Carbon Electrode Modified with Carbon Nanotubes and Celestine Blue

A simple procedure was developed to prepare a glassy carbon electrode modified with multi walled carbon nanotubes (MWCNTs) and Celestin blue. Cyclic voltammograms of the modified electrode show stable and a well defined redox couple with surface confined characteristic at wide pH range (2–12). The formal potential of redox couple (E′) shifts linearly toward the negative direction with increasing solution pH. The surface coverage of Celestine blue immobilized on CNTs glassy carbon electrode was approximately 1.95×10^?10 mol cm^?2. The charge transfer coefficient (α) and heterogeneous electron transfer rate constants (k_s) for GC/MWCNTs/Celestine blue were 0.43 and 1.26 s^?1, respectively. The modified electrode show strong catalytic effect for reduction of hydrogen peroxide and oxygen at reduced overpotential. The glucose biosensor was fabricated by covering a thin film of sol‐gel composite containing glucose oxides (GOx) on the surface of Celestine blue /MWCNTs modified GC electrode. The biosensor can be used successfully for selective detection of glucose based on the decreasing of cathodic peak current of oxygen. The detection limit, sensitivity and liner calibration rang were 0.3 μM, 18.3 μA/mM and 10 μM–6.0 mM, respectively. The accuracy of the biosensor for glucose detection was evaluated by detection of glucose in a serum sample, using standard addition protocol. In addition biosensor can reach 90% of steady currents in about 3.0 sec and interference effect of the electroactive existing species (ascorbic acid–uric acid and acetaminophen) was eliminated. Furthermore, the apparent Michaelis–Menten constant 2.4 mM, of GOx on the nano composite exhibits excellent bioelectrocatalytic activity of immobilized enzyme toward glucose oxidation. Excellent electrochemical reversibility of redox couple, high stability, technically simple and possibility of preparation at short period of time are of great advantages of this procedure for modification of glucose biosensor.     

Enhanced Electrocatalytic Reduction of Oxadiargyl and Its Determination on 2‐(4‐((4‐Acetylphenyl)diazenyl)phenylamino)‐ethanol Modified Graphene‐Paste Electrode

The electrochemical behavior of oxadiargyl at a graphene‐paste electrode modified with an azo dye, 2‐(4‐((4‐acetylphenyl)diazenyl)phenylamino)ethanol (ADPE), ADPE/MGRPE was investigated. The modified electrode showed high electrocatalytic activity toward oxadiargyl. The apparent electron transfer rate constant (k_s) and charge transfer coefficient (α) between electrode and ADPE were 1.16 s^?1 and 0.41, respectively. The differential pulse voltammetry response of the modified graphene‐paste electrode was linear against the concentration of oxadiargyl in the range from 0.03 to 1.4 mg L^?1. The limit of detection was found to be 1.3 µg L^?1 (S/N=3). The practical analytical utility of this electrode was demonstrated by measurement of oxadiargyl in river water, soil and rice samples.     

Preparation,Electrochemistry, and Electrocatalytic Activity of Lead Pentacyanonitrosylferrate Film Immobilized on Carbon Ceramic Electrode

Lead pentacyanonitrosylferrate (PbPCNF), a new Prussian blue analog, was immobilized on the surface of a carbon ceramic electrode (CCE) prepared by sol‐gel method. The immobilization process consists of adding a certain amount of metallic lead to the electrode matrix before gelation, and chemical derivatization of Pb on the electrode surface to a PbPCNF solid film by immersing the electrode in a solution of sodium pentacyanonitrosylferrate (PCNF). The composition of the synthesized PbPCNF was characterized by FTIR, scanning electron microscopy (SEM), and energy‐dispersive X‐ray (EDX) techniques. The resulting modified electrode showed electroactivity at two redox centers. The electrochemical behavior of the PbPCNF modified carbon ceramic electrode (PbPCNF|CCE) was studied by cyclic voltammetry. Under optimized conditions the peak‐to‐peak separation is only 39 mV, indicative of a surface reaction. Ion effects of the supporting electrolyte suggest that cations have a considerable effect on the electrochemical behavior of the modified electrode. The transfer coefficient (α) and the charge transfer rate constant at the modifying film|electrode interface (k_s) were calculated. The electrocatalytic activity of the modified electrode toward the electro‐reduction of peroxodisulfate was studied in details.