New Stationary Methods for Studying the Kinetics of Redox Reactions Occurring at Inert Semiconductor/Redox Electrolyte Electrodes. I. The »L ∩ P« Method

In this first paper, a new method has been theoretically grounded, for studying the kinetics of redox reactions occurring simultaneously at multielectrodes of the type inert semiconductor / redox electrolyte, representing Schottky barriers. The method is based on the simultaneously changing of both the intensity of the illumination (L), and the polarization (P), of the multielectrode; for this reason, the method has been called an »intersection method«, and symbolized by »L ∩ P«. A kinetic model has been developed to account for the effects of these dL and dP variations, in open and closed circuit conditions, and on its basis, the equations of the potentiostatic and galvanostatic »L ∩ P« methods have been obtained. Further, an expression of the specific admittance has resulted, and some particular cases are given, including that of an inert metal/redox electrolyte multielectrode

Structural and Electrochemical Characteristics of Sintered Nickel Electrodes

Sintered nickel electrodes were prepared from nickel powder ob-tained by thermolysis of Ni(NO3)2 ⋅ 6H2O and by reduction of formed oxides in controlled atmosphere and electrochemical activa-tion in 42% KOH solution. Scanning electron microscopy, X-ray diffraction and cyclic voltammetry were used to investigate the structural and electrochemical characteristics of the prepared electrodes. The diffusion coefficients of the proton in nickel hydroxide were determined. It has been found that the proton diffusion coefficient is higher for the oxidation process in 6 M KOH + 35 g/L LiOH than in 6 M KOH electrolyte. The characteristics and the performance of the prepared sintered nickel electrodes point to the possibility of their successful utilisation as cathodes in alkaline batteries

Structural and Electrochemical Characteristics of Sintered Nickel Electrodes

Sintered nickel electrodes were prepared from nickel powder ob-tained by thermolysis of Ni(NO3)2 ⋅ 6H2O and by reduction of formed oxides in controlled atmosphere and electrochemical activa-tion in 42% KOH solution. Scanning electron microscopy, X-ray diffraction and cyclic voltammetry were used to investigate the structural and electrochemical characteristics of the prepared electrodes. The diffusion coefficients of the proton in nickel hydroxide were determined. It has been found that the proton diffusion coefficient is higher for the oxidation process in 6 M KOH + 35 g/L LiOH than in 6 M KOH electrolyte. The characteristics and the performance of the prepared sintered nickel electrodes point to the possibility of their successful utilisation as cathodes in alkaline batteries

Sensitive Detection of Organophosphorus Pesticides Using a Needle Type Amperometric Acetylcholinesterase-based Bioelectrode. Thiocholine Electrochemistry and Immobilised Enzyme Inhibition

International audienceAn acetylcholinesterase (AChE) based amperometric bioelectrode for a selective detection of low concen¬ trations of organophosphorus pesticides has been developed. The amperometric needle type bioelectrode consists of a bare cavity in a PTFE isolated Pt-Ir wire, where the AChE was entrapped into a photopolymerised polymer of polyvinyl alcohol bearing styrylpyridinium groups (PVA-SbQ). Cyclic voltammetry, performed at Pt and AChE/Pt disk electrodes, confirmed the irreversible, monoelectronic thiocholine oxidation process and showed that a working potential of + 0.410 V vs. Ag/AgCl, KClSat was suitable for a selective and sensitive amperometric detection of thiocholine. The acetylthio-choline detection under enzyme kinetic control was found in the range of 0.01-0.3 U cm~" of immobilised AChE. The detection limit, calculated for an inhibition ratio of 10%, was found to reach 5 jxM for dipterex and 0.4 jaIVI for paraoxon. A kinetic analysis of the AChE-pesticide interaction process using Hanes-Woolf or Lineweaver-Burk linearisations and secondary plots allowed identification of the immobilised enzyme inhibition process as a mixed one (non/uncompetitive) for both dipterex and paraoxon. The deviation from classical Michaelis Menten kinetics induced from the studied pesticides was evaluated using Hill plots

New Stationary Methods for Studying the Kinetics of Redox Reactions Occurring at Inert Semiconductor/Redox Electrolyte Electrodes. II. The »a ∩ P« Method

In this second paper an other »intersection« method is theoretically grounded. The method is symbolized »a ∩ P«, and it is based on the simultaneously changing of both the activity (activities) of one (or more) electrochemical active species (a), and the polarization (P), of the multielectrode: inert semiconductor / redox electrolyte. Equations for the potentiostatic, respective galvanostatic »a ∩ P« methods have been deduced, and some important kinetic and electroanalytic applications, especially those referring to the inert metallredox electrolyte unielectrodes are given. These methods permit not only to determine the kinetic parameters, but also to separate the total current density j(U) into the two partial current densities j+(U), j-(U), irrespective of the electrode potential U. Finally, the expression resulted for the specific admittance is equivalent to that obtained in the first paper by using the theory of the »L ∩ P« method; this demonstrates the correctness of both »L ∩ P«, and »a ∩ P« theories

New Stationary Methods for Studying the Kinetics of Redox Reactions Occurring at Inert Semiconductor/Redox Electrolyte Electrodes. I. The »L ∩ P« Method

In this first paper, a new method has been theoretically grounded, for studying the kinetics of redox reactions occurring simultaneously at multielectrodes of the type inert semiconductor / redox electrolyte, representing Schottky barriers. The method is based on the simultaneously changing of both the intensity of the illumination (L), and the polarization (P), of the multielectrode; for this reason, the method has been called an »intersection method«, and symbolized by »L ∩ P«. A kinetic model has been developed to account for the effects of these dL and dP variations, in open and closed circuit conditions, and on its basis, the equations of the potentiostatic and galvanostatic »L ∩ P« methods have been obtained. Further, an expression of the specific admittance has resulted, and some particular cases are given, including that of an inert metal/redox electrolyte multielectrode

Influence of phosphorous acid on the nucleation and growth of copper

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Technological use of propionitrile electrosynthesis

18-24<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Propionitrile (PN) is manufactured by the non-dimerizing electroreduction of acrylonitrile. Thermodynamic calculations, kinetic studies, laboratory-scale preparative syntheses, and technological considerations made it possible to apply the electrochemical PN manufacturing on the pilot plant scale. As PN formation is kinetically favoured over adiponitrile, the yield of PN raises with increasing current densities. Endurance tests are reported for a continuous operation of the pilot plant over 7-days. Over this time period the specific material consumptions is of 1.12 kg AN (kg PN)-1, while the power usage is 4.73 kWh kg-1 The annual productivity of this type of plant is 6.53 x 103kg.</span