Search results for "Electrode"
showing 10 items of 950 documents
Thermodynamics of electrokinetic processes—II. systems with different kinds of electrodes
1990
Abstract In this work Haase's Formulation of Electrokinetic Processes is applied to special systems: those working with two different electrodes and those where gaseous phases are formed. Phenomenological equations are always written in terms of directly observable variables. The extrinsic character of Haase's Formulation is clearly shown. Some special results on streaming current in dielectric liquids are explained.
Electrochemical oxidation of organic pollutants in water at metal oxide electrodes: A simple theoretical model including direct and indirect oxidatio…
2009
Abstract The electrochemical oxidation of organics in water at metal oxide electrodes was investigated with the aim to discuss the correlations between the instantaneous current efficiency ICE and operative conditions by considering both the hypothesis of a direct oxidation process and of an indirect process mediated by adsorbed hydroxyl radicals or chemisorbed “oxygen”, in order to explicit the main differences expected between these cases. Thus, a simple theoretical model was discussed, as an extension of previous studies of Comnnellis and co-workers which were focused on indirect oxidation paths [C. Comninellis, Electrochim. Acta 39 (1994) 1857; O. Simond, V. Schaller, Ch. Comninellis, E…
Electrochemical abatement of chloroethanes in water: Reduction, oxidation and combined processes
2010
An electrochemical route, based on the anodic oxidation to carbon dioxide coupled with the cathodic reduction to de-halogenated hydrocarbons, was proposed for the treatment of waters contaminated by chloroethanes. The electrochemical abatement of two model compounds, namely 1,2-dichloroethane and 1,1,2,2-tetrachloroethane, was carried out by cathodic reduction at silver, anodic oxidation at boron doped diamond (BDD) and combined processes. The anodic oxidation gives rise to a high abatement of the concentration of both these compounds and of COD. The reduction of 1,1,2,2-tetrachloroethane proceeds also with high abatement but with the formation of some halogenated intermediates and final pr…
Electrochemical treatment of paper mill wastewater by electro-Fenton process
2019
Abstract The electrochemical oxidation of organics in paper mill wastewater belonging to Halfa industries (Tunisia) was performed by galvanostatic electrolyses using electro-Fenton (EF) process. The effect of several operating parameters, such as applied current density, electrodes material, air pressure and the presence of sodium chloride (NaCl) was evaluated. In particular, carbon felt (CF), modified carbon felt (MCF) and gas diffusion electrode (GDE) were used as cathode while Ti/IrO2-Ta2O5 and Boron Doped Diamond (BDD) as anode. Total Organic Carbon (TOC) measure was chosen as reference parameter to assess the extent of the treatment. The experimental results show that, by adopting the …
Metal- and reagent-free highly selective anodic cross-coupling reaction of phenols.
2014
The direct oxidative cross-coupling of phenols is a very challenging transformation, as homo-coupling is usually strongly preferred. Electrochemical methods circumvent the use of oxidizing reagents or metal catalysts and are therefore highly attractive. Employing electrolytes with a high capacity for hydrogen bonding, such as methanol with formic acid or 1,1,1,3,3,3-hexafluoro-2-propanol, a direct electrolysis in an undivided cell provides mixed 2,2′-biphenols with high selectivity. This mild method tolerates a variety of moieties, for example, tert-butyl groups, which are not compatible with other strong electrophilic media but vital for later catalytic applications of the formed products.
Performance comparison of mono-polar and bi-polar configurations of alkaline electrolysis stack through 3-D modelling and experimental fabrication
2020
Abstract Generation of hydrogen using electrolysis process with integrated renewable energy sources is highly important especially in environmental aspects. In this paper, we demonstrate that the enhancement of electrolysis performance of alkaline electrolysis stacks by diminishing the distance between electrodes, while changing the properties of the Membrane Electrode Assembly (MEA). Prior to that, the performances of mono-polar and bi-polar configurations of alkaline electrolysis stack are compared through 3-D modelling and experimental fabrication. At first, two different single cell alkaline electrolysers are designed using SolidWorks as a design software and the designed cell has been …
CO2 turned into a nitrogen doped carbon catalyst for fuel cells and metal–air battery applications
2021
Heteroatom doped metal-free catalysts are one of the most promising replacements for platinum for the alkaline oxygen reduction reaction (ORR). Due to the lack of metal atoms, they are extremely stable and environmentally friendly. However, production of carbon nanomaterials can have a very high CO2 footprint. In this study, we present ORR catalysts made directly from CO2via molten salt CO2 electrolysis. The deposited carbon powder is doped with nitrogen using pyrolysis in the presence of dicyandiamide. The effect of molten carbonate electrolyte composition towards the final ORR activity in 0.1 M KOH is studied. A thorough physico-chemical study of the starting carbons and N-doped catalysts…
An impedance study of complex Al/Cu-Al2O3electrode
2011
Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equival…
Electrochemical incineration of 1,2-dichloroethane: Effect of the electrode material
2008
The electrochemical incineration of 1,2-dichloroethane (EDC) at Pt, Au, boron-doped diamond (BDD), Ebonex, stainless steel, Ti/IrO2–Ta2O5 and PbO2 has been studied in acid media by cyclic voltammetry and bulk electrolysis. It has been shown that the performances of the process dramatically depend on the anodic material. Higher current efficiencies were obtained at BDD. In particular, at proper values of applied current density, it is possible to obtain the almost complete conversion of EDC to CO2 at BDD with current efficiencies higher than 40%.
Electrochemistry as an Attractive and Effective Tool for the Synthesis and Immobilization of Porphyrins on an Electrode Surface
2014
Magnesium(II) 10-phenyl-5,15-p-ditolylporphyrin is easily and cleanly transformed by electrolysis. A nitro group is first introduced at the free meso position by anodic substitution. Hydrogenation into the amine is then carried out electrocatalytically under ambient conditions with water as a hydrogen supplier. The synthesized porphyrin under the nickel(II) form can be covalently grafted onto a platinum electrode by electrochemical reduction of the diazonium cation, generated in situ by a reaction of the nickel(II) aminoporphyrin with sodium nitrite and trifluoroacetic acid. The electrosynthesized thin film gives an electrochemical response typical of a porphyrin material. Films grown under…