464 resultados para Platinum electrode
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
The mechanism of formic acid electrooxidation on iron tetrasulfophthalocyanine (FeTSPc) modified Pt electrode was investigated with electrochemical methods. It was found that a "third-body" effect of FeTSPc on Pt electrode predominates during the electrooxidation process based on unusual electrochemical results. The modification leads formic acid electrooxidation to take place through a desired direct pathway, in which the mechanism is proposed to be the gradual dehydrogenation of formic acid and the reaction of formate with hydroxyl species.
Resumo:
The effect of metal cations in solution on the oxidation of methanol on the electrode surface of platinum is a neglected aspect to direct methanol fuel cell (DMFC). In this paper, a smooth platinum electrode absorbing metal cations as the working electrode was applied to investigate the methanol oxidation with the cyclic voltammetry (CV) in 1.0 mol L-1 H2SO4. From the analysis of experiment, it is found that the cations, Li+, Ce4+, Mn2+, Ni2+, Cu2+, have some negative effect on the catalytic oxidation of methanol on the surface of platinum. The degree of the effect from different cations was analyzed.
Resumo:
The influence of K7Fe3+P2W17O62H2 on l-alpha-phosphatidylcholine/cholesterol bilayer lipid membrane on Pt electrode was studied by voltammetry and AC impedance spectroscopy. The interaction of the polyoxometalates with the BLM can promote the access of Ru(NH3)(6)(3+) and [Fe(CN)(6)](3-/4-) to the electrode surface. It was found that some kind of pores had been formed on the BLM by AFM. The phenomenon is attributed to the interaction of K7Fe3+P2W17O62H2 with phosphatidylcholine phosphate groups located in its outer leaflet. Experimental results are helpful to understand the biological activity of the polyoxometalates in vivo.
Resumo:
The microregion approximation explicit finite difference method is used to simulate cyclic voltammetry of an electrochemical reversible system in a three-dimensional thin layer cell with minigrid platinum electrode. The simulated CV curve and potential scan-absorbance curve were in very good accordance with the experimental results, which differed from those at a plate electrode. The influences of sweep rate, thickness of the thin layer, and mesh size on the peak current and peak separation were also studied by numerical analysis, which give some instruction for choosing experimental conditions or designing a thin layer cell. The critical ratio (1.33) of the diffusion path inside the mesh hole and across the thin layer was also obtained. If the ratio is greater than 1.33 by means of reducing the thickness of a thin layer, the electrochemical property will be far away from the thin layer property.
Resumo:
Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous detection of hydrazine, methylhydrazine, and isoniazid has been developed with a 4-pyridyl hydroquinone self-assembled microdisk platinum electrode. Such an electrode has very high catalytic ability for hydrazines and they could be detected even at 0.0 V. The responses for hydrazine, methylhydrazine, and isoniazid are linear over 3 orders of detected concentration and of magnitude of 0.2-400 mu M, 0.2-400 mu M, 0.5 mu M-2 mM, with correlation coefficients of 0.9998, 0.9991, and 0.9982, respectively. And they could be detected to levels of 0.1, 0.1 and 0.2 mu M, respectively. This modified electrode was found to be very stable and reproducible when continuously used as detector for capillary electrophoresis for period of at least 4 weeks with no apparent loss of response. (C) 1999 Elsevier Science B.V. All rights reserved.
Resumo:
4-Pyridyl hydroquinone on a platinum electrode adsorbs through the pyridine nitrogen forming stable self-assembled layers. The electrocatalytical oxidation of hydrazines was performed by the modified electrode. The overpotential of hydrazines was decreased markedly at the self-assembled monolayer (SAM) electrode. The mechanism of hydrazine oxidation was also investigated. Amperometric detection of hydrazine under zero potential (vs Ag\AgCI\sat. KCl) was exhibited by the SAM electrode used as an electrochemical detector in a flow system. (C) 1998 Elsevier Science S.A. All rights reserved.
Resumo:
The electrochemically deposited poly(o-phenylenediamine) film on a Pt electrode has been investigated utilizing in situ external reflection FTIR spectroelectrochemistry technique. The prepared ladder polymer film is found to be partially ring-opened. The dopant ClO4- is evidenced to orient in such a way that more than one oxygen atom attach to the charge sites of the polymer. This suggests that positive charges of oxidized polymer are partially delocalized over the whole chains. The proton movement observed during the oxidation reaction is associated with the solvated MeCN molecule. It is proposed that the proton diffusion, dissolvation and protonation of the film may be essential to the electrochemical reduction reaction of the film. Copyright (C) 1996 Elsevier Science Ltd.
Resumo:
The electrochemical redox behavior of bilirubin (BR IValpha), biliverdin (BV IValpha) and their oxidized product bile-purpurin (Bi-Pu) have been studied by in situ spectroelectrochemical techniques, which reveals that the transformation of BR IValpha [GRA
Resumo:
The poisonous intermediate of methanol oxidation on a Pt electrode was validated to be COad by electrochemical method. An approximate treatment to bimolecular elementary reactions on an electrode was advanced and then was applied to the stripping normal pulse voltammetry (NPV) for complex multistep multielectron transfer processes on plane electrodes to study the kinetics of completely irreversible process Of COad oxidation to CO2. The kinetic parameters for this process, such as standard rate constant (0) and anodic transfer coefficient (alpha) for this irreversible heterogeneous electron-transfer process at electrode/solution interface and apparent diffusion coefficient (D-app) for charge-transfer process within the monolayer of COad on electrode surface, were obtained with stripping NPV method. The effect of the approximate treatment on the kinetic parameters was also analyzed.
Resumo:
A stable electroactive thin film of cobalt hexacyanoferrate (CoHCF) was electrochemically deposited on the surface of a glassy carbon (GC) electrode with a new and simple method. The cyclic voltammograms of the CoHCF Film modified GC (CoHCF/GC) electrode prepared by this method exhibit two pairs of well-defined redox peaks, at scan rates up to 200 mV s(-1). The advantage of this method is that it is easy to manipulate and to control the surface coverage of CoHCF on the electrode surface. The modified electrode shows good electrocatalytic activity towards the electrochemical reaction of dopamine (DA) in a 0.1 mol dm (3) KNO3 + phosphate buffer solution (pH 7.0). The rate constant of the electrocatalytic oxidation of DA at the CoHCF/GC electrode is determined by employing rotating disk electrode measurements.
Resumo:
A droplet of aqueous solution containing a certain molar ratio of redox couple is first attached onto a platinum electrode surface, then the resulting drop electrode is immersed into the organic solution containing very hydrophobic electrolyte. Combined with reference and counter electrodes, a classical three-electrode system has been constructed, Ion transfer (IT) and electron transfer (ET) are investigated systematically using three-electrode voltammetry. Potassium ion transfer and electron transfer between potassium ferricyanide in the aqueous phase and ferrocene in nitrobenzene are observed with potassium ferricyanide/potassium ferrocyanide as the redox couple. Meanwhile, the transfer reactions of lithium, sodium, potassium, proton and ammonium ions are obtained with ferric sulfate/ferrous sulfate as the redox couple. The formal transfer potentials and the standard Gibbs transfer energy of these ions are evaluated and consistent with the results obtained by a four-electrode system and other methods.