382 research outputs found
Enhancement of photovoltaic performance using aĀ novel photocathode based on poly(3,4-ethylenedioxythiophene)/AgāCuO nanocomposite in dye-sensitized solar cells
A novel counter electrode (CE) based on a silver and copper oxide nanocomposite is developed and characterized by XRD and FE-SEM. A polymeric system containing poly(3,4-ethylenedioxythiophene) (PEDOT) is employed as the conductive polymer to prepare a transparent CE for a dye-sensitized solar cell (DSSC) device. Electrochemical analysis is used to study the catalytic activity of the reduction of triiodide ions in different DSSC-based CEs. To study the effect of photoelectrode modification on charge-transfer resistance, alternating current impedance spectroscopy is carried out. Power conversion efficiency and short-circuit current density () increase from 8.01% to 9.06% and 16.18 to 17.79 mA/cm2, respectively, due to the significantly improved electrical conductivity and electrocatalytic activity of the novel PEDOT/AgāCuO nanocomposite-based CE
Enhancement of photovoltaic performance using aĀ novel photocathode based on poly(3,4-ethylenedioxythiophene)/AgāCuO nanocomposite in dye-sensitized solar cells
A novel counter electrode (CE) based on a silver and copper oxide nanocomposite is developed and characterized by XRD and FE-SEM. A polymeric system containing poly(3,4-ethylenedioxythiophene) (PEDOT) is employed as the conductive polymer to prepare a transparent CE for a dye-sensitized solar cell (DSSC) device. Electrochemical analysis is used to study the catalytic activity of the reduction of triiodide ions in different DSSC-based CEs. To study the effect of photoelectrode modification on charge-transfer resistance, alternating current impedance spectroscopy is carried out. Power conversion efficiency and short-circuit current density () increase from 8.01% to 9.06% and 16.18 to 17.79 mA/cm2, respectively, due to the significantly improved electrical conductivity and electrocatalytic activity of the novel PEDOT/AgāCuO nanocomposite-based CE
Electrocatalytic Behavior of Levodopa at MultiWall Carbon Nanotubes and 4-((E)-(2-Methyl-4-Nitrophenylimino) Methyl) Benzene-1,2-Diol Modified Glassy Carbon Electrode
This work describes a glassy carbon electrode (GCE) modified by 4-((E)-(2-methyl-4-nitrophenylimino)
methyl) benzene-1,2-diol (abbreviated as MBD) and multiwall carbon nanotubes (MWNT) as an electrochemical
sensor for monitoring of levodopa (LD) concentration. Different electrochemical parameters of
MBD were obtained at MWCNT-GCE by cyclic voltammetry. Also the electrocatalytic behavior of LD was
investigated at the MBD-MWNT-GCE by cyclic voltammetry, chronoamperometry and differential pulse
voltammetry. Using the electrocatalysis of LD V in phosphate buffer solution pH 7.0 on this modified electrode
it is possible to obtain a linear calibration curve from 5.0 10 ā 7 to 9.0 10 ā 4 M and a detection limit
of 0.37 Ī¼M for LD by differential pulse voltammetry. The electrode was successfully applied for determination
of LD in real sample.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3493
Preparation and electrochemical application of rutin biosensor for differential pulse voltammetric determination of NADH in the presence of acetaminophen
The electrocatalytic behavior of reduced nicotinamide adenine di-nucleotide (NADH) was studied at the surface of a rutin biosensor, using various electrochemical methods. According to the results, the rutin biosensor had a strongly electrocatalytic effect on the oxidation of NADH with the overpotential being decreased by about 450 mV as compared to the process at a bare glassy carbon electrode, GCE. This value is significantly greater than the value of 220 mV that was reported for rutin embedded in a lipid-cast film. The kinetic parameters of the electron transfer coefficient, a, and the heterogeneous charge transfer rate constant, kh, for the electrocatalytic oxidation of NADH at the rutin biosensor were estimated. Furthermore, the linear dynamic range; sensitivity and limit of detection for NADH were evaluated using the differential pulse voltammetry method. The advantages of this biosensor for the determination of NADH are excellent catalytic activity and reproducibility, good detection limit and high exchange current density. The rutin biosensor could separate the oxidation peak potentials of NADH and acetaminophen present in the same solution while at a bare GCE, the peak potentials were indistinguishable
Spectrophotometric determination of the acidity constants of calcon in water and mixed waterāorganic solvents
The acidābase properties of calcon (1-(2-hydroxy-1-naphthylazo)-2-naphthol-4-sulfonic acid) in water and mixed waterāorganic solvents at 25 Ā°C at an ionic strength of 0.10 M are studied by a multiwavelength spectrophotometric method. The organic solvents used were the amphiprotic (methanol), dipolar aprotic (dimethylsulfoxide), and low basic aprotic (acetonitrile). To evaluate the pH absorbance data, a resolution method based on the combination of soft- and hard-modeling was applied. The acidity constants of all related equilibria were estimated using the whole spectral fitting of the collected data to an established factor analysis model. The data analysis program Datan was applied for determination of the acidity constants. The corresponding pKa values were determined in water and mixed waterāorganic solvents. Linear relationship between the acidity constants and the mole fraction of the different sol-vents in the mixtures exist. The effect of solvent properties on acidābase behavior is discussed
Simultaneous Kinetic Spectrophotometric Determination of Hydrazine and Isoniazid Using H-Point Standard Addition Method and Partial Least Squares Regression in Micellar Media
The present study describes the application of simultaneous kinetic spectrophotometric determination of hydrazine (HZ) and isoniazid (INH), using H-point standard addition method (HPSAM) and partial least squares (PLS) calibration. The methods are based on the difference observed in the rate of iron (III) reduction with HZ and INH, in the presence of 2,2\u27-bipyridine (Bpy) and the subsequent complex formation between the resulted Fe2+ and Bpy in a solution containing sodium dodecyl sulfate (SDS) as a micellar medium. INH and HZ can simultaneously be determined between the range of 0.08ā6.0 and 1.0ā80.0 Ī¼g mLā1, respectively. The results have shown that by the application of HPSAM, the simultaneous determination could be performed with the ratio of 1:1000 to 1:12.5 for INH-HZ. Through the HPSAM analysis, the relative standard deviations of HZ and INH were 2.5 and 1.2, respectively. The total relative standard error for applying the PLS method to 9 synthetic samples, in the concentration ranges of 0.0ā20.0 Ī¼g mLā1 of HZ and 0.5ā3.0 Ī¼g mLā1 of INH, was 3.19. Both proposed methods (PLS and HPSAM) were successfully applied to the simultaneous determination of HZ and INH in several commercially available isoniazid formulations and satisfactory results were obtained.</p
Oxidized multi walled carbon nanotubes for improving the electrocatalytic activity of a benzofuran derivative modified electrode
In the present paper, the use of a novel carbon paste electrode modified by 7,8-dihydroxy-3,3,6-trimethyl-3,4-dihydrodibenzo[b,d]furan-1(2H)-one (DTD) and oxidized multi-walled carbon nanotubes (OCNTs) is described for determination of levodopa (LD), acetaminophen (AC) and tryptophan (Trp) by a simple and rapid method. At first, the electrochemical behavior of DTD is studied, then, the mediated oxidation of LD at the modified electrode is investigated. At the optimum pH of 7.4, the oxidation of LD occurs at a potential about 330 mV less positive than that of an unmodified carbon paste electrode. Based on differential pulse voltammetry (DPV), the oxidation current of LD exhibits a linear range between 1.0 and 2000.0 Ī¼M of LD with a detection limit (3Ļ) of 0.36 Ī¼M. DPV was also used for simultaneous determination of LD, AC and Trp at the modified electrode. Finally, the proposed electrochemical sensor was used for determinations of these substances in human serum sample
[Bis(2-hydroxyl imino)1-phenyl, 2-(2-qunolile)1-ethanona]Aluminium(III) Complex as Carrier for a Salicylate-Sensitive Electrode
A salicylate-selective electrode based on the complex [bis(2-hydroxyl imino)1-phenyl,2-(2- qunolile)1-ethanona]Aluminium(III) as the membrane carrier was developed. The electrode exhibited a good Nernstian slope of ā59.1 Ā± 0.4 mV / decade (mean value Ā± standard deviation, n = 5) and a linear range of 1.0 Ć 10ā6ā 1.0 Ć 10ā1 mol Lā1 for salicylate. The limit of detection was 5.0 Ć 10ā7 mol Lā1. The electrode had a fast response time of 15 s and could be used for more than three months. The selectivity coefficients were determined by the fixed interference method (FIM) and could be used in the pH range of 2.0ā7.8. It was employed as an indicator electrode for direct the determination of salicylate in pharmaceutical samples
Electrochemical sensor based on multi-walled carbon nanotubes and 4-(((4-mercaptophenyl)imino)methyl) benzene-1,2-diol for simultaneous determination of epinephrine in the presence of acetaminophen
A carbon paste electrode modiļ¬ed with 4-(((4-mercaptophenyl)imino)methyl)benzene-1,2-diol (MIB) and multi-walled carbon nanotubes MIB /CNT/CPE) was prepared for determination of epinefrine (EP) in the presence of acetaminophen (AC). Cyclic voltammetry, chronoamperometry and differential pulse voltammetry (DPV) techniques were used to investigate the modiļ¬ed electrode for the electrocatalytic oxidation of (EP) and (AC) in aqueous solutions. The separation of the oxidation peak potential for EP- AC was 200 mV. Under the optimum conditions, the calibration curve for EP was obtained in the range of 1.0 to 25.0 ĀµM and 25.0 to 500.0 ĀµM. The diffusion coefļ¬cient for the oxidation of EP at the surface of modiļ¬ed electrode was calculated as 5.76Ć10-5 cm2s-1.</p
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