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Electrocatalytic Oxidation (electrocatalytic + oxidation)
Selected AbstractsInfluence of Metal Nanoparticles on the Electrocatalytic Oxidation of Glucose by Poly(NiIIteta) Modified ElectrodesELECTROANALYSIS, Issue 5 2010Pratap Azad Abstract Conductive polymeric [NiII(teta)]2+ (teta=C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) films (poly(Ni)) have been deposited on the surface of glassy carbon (GC), Nafion (Nf) modified GC (GC/Nf) and Nf stabilized Ag and Au nanoparticles (NPs) modified GC (GC/Ag-Nf and GC/Au-Nf) electrodes. The cyclic voltammogram of the resulting electrodes, show a well defined redox peak due to oxidation and reduction of poly(Ni) system in 0.1,M NaOH. They show electrocatalytic activity towards the oxidation of glucose. AFM studies reveal the formation of poly(Ni) film on the modified electrodes. Presence of metal NPs increases electron transfer rate and electrocatalytic oxidation current by improving the communication within the Nf and poly(Ni) films. In the presence of metal NPs, 4 fold increase in current for glucose oxidation was observed. [source] Electrocatalytic Oxidation of Glucose by the Glucose Oxidase Immobilized in Graphene-Au-Nafion BiocompositeELECTROANALYSIS, Issue 3 2010Kangfu Zhou Abstract Graphene was successfully prepared and well separated to individual sheets by introducing SO3,. XRD and TEM were employed to characterize the graphene. UV-visible absorption spectra indicated that glucose oxidase (GOx) could keep bioactivity well in the graphene-Au biocomposite. To construct a novel glucose biosensor, graphene, Au and GOx were co-immobilized in Nafion to further modify a glassy carbon electrode (GCE). Electrochemical measurements were carried out to investigate the catalytic performance of the proposed biosensor. Cyclic voltammograms (CV) showed the biosensor had a typical catalytic oxidation response to glucose. At the applied potential +0.4,V, the biosensor responded rapidly upon the addition of glucose and reached the steady state current in 5,s, with the present of hydroquinone. The linear range is from 15,,M to 5.8,mM, with a detection limit 5,,M (based on the S/N=3). The Michaelis-Menten constant was calculated to be 4.4,mM according to Lineweaver,Burk equation. In addition, the biosensor exhibits good reproducibility and long-term stability. Such impressive properties could be ascribed to the synergistic effect of graphene-Au integration and good biocompatibility of the hybrid material. [source] Preparation and Characterization of a Tin Pentacyanonitrosylferrate-Modified Carbon Ceramic Electrode: Application to Electrocatalytic Oxidation and Amperometric Detection of L -CysteineELECTROANALYSIS, Issue 7 2009H. Razmi Abstract The sol-gel technique was used to construct tin pentacyanonitrosylferrate (SnPCNF) modified composite carbon ceramic electrode (CCE). This involves two steps: construction of CCE containing metallic Sn powder and then electrochemical creating of SnPCNF on the surface of CCE. The SnPCNF modified CCE (SnPCNFlCCE) was characterized by energy-dispersive X-ray (EDX), FTIR and cyclic voltammetry (CV) techniques. The SnPCNF film showed electrocatalytic activity toward the oxidation of L -cysteine. A linear calibration plot was obtained over the L -cysteine concentration range 1,51,,M using chronoamperometry. L -cysteine was determined amperometrically at the surface of this modified electrode. The detection limit (for a signal to noise of 3) and sensitivity were found to be 0.62,,M and 126,,A/mM, respectively. [source] Electrocatalytic Oxidation and Voltammetric Determination of Hydrazine on the Tetrabromo- p -Benzoquinone Modified Carbon Paste ElectrodeELECTROANALYSIS, Issue 5 2007Jahan-Bakhsh Raoof Abstract The electrochemical properties of hydrazine studied at the surface of a carbon paste electrode spiked with p -bromanil (tetrabromo- p -benzoquinone) using cyclic voltammetry (CV), double potential-step chronoamperometry and differential pulse voltammetry (DPV) in aqueous media. The results show this quinone derivative modified carbon paste electrode, can catalyze the hydrazine oxidation in an aqueous buffered solution. It has been found that under the optimum conditions (pH,10.00), the oxidation of hydrazine at the surface of this carbon paste modified electrode occurs at a potential of about 550,mV less positive than that of a bar carbon paste electrode. The electrocatalytic oxidation peak current of hydrazine showed a linear dependent on the hydrazine concentrations and linear analytical curves were obtained in the ranges of 6.00×10,5 M,8.00×10,3 M and 7.00×10,6 M,8.00×10,4 M of hydrazine concentration with CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3,) were determined as 3.6×10,5 M and 5.2×10,6 M by CV and DPV methods. This method was also used for the determination of hydrazine in the real sample (waste water of the Mazandaran wood and paper factory) by standard addition method. [source] Electrocatalytic Oxidation of Sulfur Containing Amino Acids at Renewable Ni-Powder Doped Carbon Ceramic Electrode: Application to Amperometric Detection L -Cystine, L -Cysteine and L -MethionineELECTROANALYSIS, Issue 21 2006Abdollah Salimi Abstract A sol-gel technique was used here to prepare a renewable carbon ceramic electrode modified with nickel powder. Cyclic voltammograms of the resulting modified electrode show stable and a well defined redox couple due to Ni(II)/Ni(III) system with surface confined characteristics. The modified electrode shows excellent catalytic activity toward L -cystine, L -cysteine and L -methionine oxidation at reduced overpotential in alkaline solutions. In addition the antifouling properties at the modified electrode toward the above analytes and their oxidation products increases the reproducibility of results. L -cystine, L -cysteine and L -methionine were determined chronoamperometricaly at the surface of this modified electrode at pH range 9,13. Under the optimized conditions the calibration curves are linear in the concentration range 1,450,,M, 2,90,,M and 0.2,75,,M for L -cystine, L -methionine and L -cysteine determination, respectively. The detection limit and sensitivity were 0.64,,M, 3.8,nA/ ,M for L -cystine, 2,,M, 5.6,nA/ ,M for L -methionine and 0.2,,M and 8.1,nA/,M for L -cysteine. The advantageous of this modified electrode is high response, good stability and reproducibility, excellent catalytic activity for oxidation inert molecules at reduced overpotential and possibility of regeneration of the electrode surface by potential cycling for 5,minutes. Furthermore, the modified electrode has been prepared without using specific reagents. This sensor can be used as an amperometric detector for disulfides detection in chromatographic or flow systems. [source] Electrocatalytic Oxidation of NADH by Oxidized s-Adenosyl-L-Methionine (SAMe): Application to NADH and SAMe DeterminationsELECTROANALYSIS, Issue 11 2004Noemí de-los-Santos-Álvarez Abstract s -Adenosyl- L -methionine (SAMe) is an adenosine analogue with therapeutical activity against affective disorders and liver dysfunctions. It can be oxidized on graphite electrode yielding a strongly adsorbed electroactive oxidation product for which a quinone-imine structure is proposed. This compound is capable of electrocatalyzing the NADH oxidation at low potentials, lowering the overvoltage by about 300,mV. An amperometric method for NADH determination at +0.1,V (Ag|AgCl|KClsat) is developed using an oxidized-SAMe-modified electrode in pH,9. Linear calibration plots were obtained with a detection limit of 2.4,nM. The electrode response time and the relative standard deviation of the slope of the calibration plot for 5 different modified electrodes were 12,s and 5.6% respectively. The catalytic scheme also provides the first method to determine SAMe itself by adsorptive differential pulse voltammetry. The linear range was found to be 42.4,424,nM with a reproducibility of 6.9%. The method was applied to SAMe determination in a pharmaceutical formulation. [source] New Strategy for Dehydrogenase Amperometric Biosensors Using Surfactant to Enhance the Sensitivity of Diaphorase/Ferrocene Modified Carbon Paste Electrodes for Electrocatalytic Oxidation of NADHELECTROANALYSIS, Issue 13 2003César Ramírez-Molina Abstract A carbon paste electrode (CPE) modified with diaphorase (DAP) and ferrocene (FcH) has been developed for determination of NADH at low working potential. The sensitivity and operational stability, towards the detection of the reduced form of the nicotinamide adenine dinucleotide (NADH) in flow injection analysis (FIA), were greatly improved (5 times) upon adding Tween 20 into the electrode matrix. The magnitude of the amperometric signal was dependent on DAP, FcH and surfactant loading, into the modified carbon paste electrode. A rapid and repeatable response was observed to the variation of NADH concentration in the vicinity of the electrode surface. Such advantages of the DAP/FcH/Tween 20 modified carbon paste were successfully used in the construction of L -lactate dehydrogenase modified electrodes. The use of this new approach can be generalized to other dehydrogenases and represents a decisive step for a versatile preparation method of amperometric biosensors. [source] ChemInform Abstract: Selective Electrocatalytic Oxidation of N-Alkyl-N-methylanilines to N-Alkylformanilides Using Nitroxyl Radical.CHEMINFORM, Issue 32 2001Yoshitomo Kashiwagi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Electrocatalytic Oxidation of Nitrite at Gold Nanoparticle- polypyrrole Nanowire Modified Glassy Carbon ElectrodeCHINESE JOURNAL OF CHEMISTRY, Issue 12 2009Jing Li Abstract A novel chemically modified electrode based on the dispersion of gold nanoparticles on polypyrrole nanowires has been developed to investigate the oxidation behavior of nitrite using cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques. The diffusion coefficient (D), electron transfer coefficient (,) and charge transfer rate constant (k) for the oxidation of nitrite were determined. The modified electrode exhibited high electrocatalytic activity toward the oxidation of nitrite. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0×10,7,2.5×10,3 mol·L,1 with a detection limit of 1.0×10,7 mol·L,1 (s/n=3). The proposed method was successfully applied to the detection of nitrite in water samples with obtained satisfactory results. Additionally, the sensor also showed excellent sensitivity, anti-interference ability, reproducibility and stability properties. [source] Electrocatalytic oxidation of vitamin B6 by 4-hydroxy-2,2,6,6-tetramethylpiperidine- N -oxylCHINESE JOURNAL OF CHEMISTRY, Issue 11 2004Yan Li Abstract The electrochemistry of pyridoxine (vitamin B6, VB6) was studied by cyclic voltammetry at a glassy carbon electrode. The electrochemical response of VB6 could be significantly enhanced by using 4-hydroxy-2,2,6,6-tetra-methylpiperidine- N -oxyl (HO-TEMPO) as a mediator via an electrocatalytic EC' mechanism with the oxoammonium ion of HO-TEMPO as the active oxidant. The catalytic rate constant was determined to be 5.4×103 (mol*L,1),1*s,1 by using chronomperometq. [source] Simultaneous Determination of Ascorbic Acid, Dopamine and Uric Acid at Pt Nanoparticles Decorated Multiwall Carbon Nanotubes Modified GCEELECTROANALYSIS, Issue 10 2010Zekerya Dursun Abstract A modified electrode was fabricated by electrochemically deposition of Pt nanoparticles on the multiwall carbon nanotube covered glassy carbon electrode (Pt nanoparticles decorated MWCNT/GCE). A higher catalytic activity was obtained to electrocatalytic oxidation of ascorbic acid, dopamine, and uric acid due to the enhanced peak current and well-defined peak separations compared with both, bare and MWCNT/GCE. The electrode surfaces were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). Individual and simultaneous determination of AA, DA, and UA were studied by differential pulse voltammetry. The detection limits were individually calculated for ascorbic acid, dopamine, and uric acid as being 1.9×10,5,M, 2.78×10,8,M, and 3.2×10,8,M, respectively. In simultaneous determination, LODs were calculated for AA, DA, and UA, as of 2×10,5,M, 4.83×10,8,M, and 3.5×10,7,M, respectively. [source] | ||||||||||