The application of strong electric fields in water and organic liquids has been studied for several years, because of its importance in electrical transmission processes and its practical applications in biology, chemistry, and electrochemistry. More recently, liquid-phase electrical discharge reactors have been investigated, and are being developed, for many environmental applications, including drinking water and wastewater treatment, as well as, potentially, for environmentally benign chemical processes. This paper reviews the current status of research on the application of high-voltage electrical discharges for promoting chemical reactions in the aqueous phase, with particular emphasis on applications to water cleaning.

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Electrohydraulic Discharge and Nonthermal Plasma for Water Treatment

We report the discovery of a highly active Ni−Co alloy electrocatalyst for the oxidation of hydrazine (N2H4) and provide evidence for competing electrochemical (faradaic) and chemical (nonfaradaic) reaction pathways. The electrochemical conversion of hydrazine on catalytic surfaces in fuel cells is of great scientific and technological interest, because it offers multiple redox states, complex reaction pathways, and significantly more favorable energy and power densities compared to hydrogen fuel. Structure−reactivity relations of a Ni60Co40 alloy electrocatalyst are presented with a 6-fold increase in catalytic N2H4 oxidation activity over today’s benchmark catalysts. We further study the mechanistic pathways of the catalytic N2H4 conversion as function of the applied electrode potential using differentially pumped electrochemical mass spectrometry (DEMS). At positive overpotentials, N2H4 is electrooxidized into nitrogen consuming hydroxide ions, which is the fuel cell-relevant faradaic reaction pathway....

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Noble metal-free hydrazine fuel cell catalysts: EPOC effect in competing chemical and electrochemical reaction pathways.

Philippe Vernoux,*,† Leonardo Lizarraga,† Mihalis N. Tsampas,† Foteini M. Sapountzi,† Antonio De Lucas-Consuegra,‡ Jose-Luis Valverde,‡ Stamatios Souentie, Costas G. Vayenas, Dimitris Tsiplakides, Stella Balomenou, and Elena A. Baranova †Universite de Lyon, Institut de Recherches sur la Catalyse et l’Environnement de Lyon, UMR 5256, CNRS, Universite Claude Bernard Lyon 1, 2 Avenue A. Einstein, 69626 Villeurbanne, France ‡Departamento de Ingenieria Quimica, Facultad de Ciencias y Tecnologias Quimicas, Universidad de Castilla-La Mancha, Avenida Camilo Jose Cela 10, 13005 Ciudad Real, Spain LCEP, Caratheodory 1 Street, Department of Chemical Engineering, University of Patras, Patras GR-26500, Greece Division of Natural Sciences, Academy of Athens, Panepistimiou 36 Avenue, GR-10679, Athens, Greece Chemical Process Engineering Research Institute (CPERI), Centre for Research and Technology−Hellas (CERTH), Thessaloniki, Greece Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis-Pasteur Ottawa, Ontario K1N 6N5, Canada

Ionically conducting ceramics as active catalyst supports.

Hypo–hyper-d-electronic interactive nature of interionic synergism in catalysis and electrocatalysis for hydrogen reactions

The influence of glass corrosion on the electrocatalytic activity of fuel cell catalysts was studied. A Teflon electrochem. cell was designed for measurements in alk. electrolyte. The cell performance was tested and compared to a std. electrochem. glass cell by measuring the O redn. reaction and the H oxidn. reaction on polycryst. Pt in 0.1M KOH. In the Teflon cell the shape of the cyclic voltammogram as well as the activity for the reactions are reproducible and do not alter over a long period of time. By comparison, using the std. electrochem. cell made out of Duran glass, the expts. on polycryst. Pt electrodes in alk. electrolyte are insufficiently reproducible. The cyclic voltammograms alter over time, and the activities for H oxidn. as well as O redn. depend on the applied potential scan limits. This is due to the contamination of the electrolyte because of the etching of glass by KOH - anal. of the alk. electrolyte after usage in the resp. cell types by ICP-OES confirmed this suggestion. [on SciFinder(R)]

Impact of Glass Corrosion on the Electrocatalysis on Pt Electrodes in Alkaline Electrolyte

THE rates of many heterogeneous catalytic reactions between gaseous adsorbates on metal surfaces supported on solid electrolytes can be increased by applying a potential to the metal1–8 This phenomenon, which has been reported previously at temperatures of 250–750°C, has been shown9 to be due to the electrochemically induced spillover of ions from the support onto the catalyst surface; the ions then act as promoters for the catalytic reaction Here we report that a similar effect can be observed in aqueous solution at ambient temperatures We studied the oxidation of H2 on a platinum/graphite electrode immersed in aqueous KOH Application of a positive potential of 1–2 V to the Pt electrode increased the rate of H2 oxidation by up to 500% We deduce that hydroxide ions are acting as promoters, and find that each ion supplied to the catalyst causes the oxidation of up to 20 hydrogen atoms This kind of rate enhancement for heterogeneous catalytic reactions in solution may be of considerable technological value, for example in the electrochemical treatment of toxic organics10 or the generation of useful industrial chemicals4

Electrochemical enhancement of a catalytic reaction in aqueous solution

The heterogeneous catalytic oxidation of H2 on Pt was investigated on Pt black and Pt−graphite electrodes, also serving as heterogeneous catalysts, in aqueous alkaline solutions as a function of electrode potential and current. Hydrogen−oxygen mixtures were bubbled over the surface of the Pt electrode through a porous Teflon frit, and the rates of H2 and O2 consumption were measured via on-line mass spectrometry and gas chromatography. It was found that positive current application enhances the catalytic rate of H2 oxidation by up to 500% and that the increase in the catalytic rate is up to 100 times larger than the increase I/2F of the electrocatalytic rate corresponding to Faraday's law. The results show that the heterogeneously catalyzed H2 oxidation proceeds in parallel with the electrocatalytic anodic H2 oxidation and that its rate is markedly affected by the catalyst potential and work function. This electrochemically induced and controlled reversible promotion of the catalytic properties of Pt bear...

P. Stonehart

Papers

Electrochemical enhancement of a catalytic reaction in aqueous solution

Non-Faradaic Electrochemical Modification of the Catalytic Activity of Pt for H2 Oxidation in Aqueous Alkaline Media