Indirect Oxidation of Organic Substances by Intermediates of the Oxygen Reduction

Results of two urgent and practically important directions of research on the indirect oxidation of organic compounds by highly reactive intermediates generated electrochemically from oxygen (HO₂ ^–, HO₂ ^·, HO^·) are considered and orderly arranged. The studies in question are the indirect synthesis and mineralization of organic toxicants in waste water.     

Use of aqueous hydrogen peroxide solutions prepared by cathodic reduction of oxygen for indirect oxidation of chemical substances in situ: Achievements and prospects

The achievements and prospects in the use of aqueous hydrogen peroxide solutions prepared by cathodic reduction of oxygen in carbon black gas-diffusion and graphite electrodes for indirect oxidation of organic and inorganic substrates in situ are analyzed. Specific examples demonstrate the efficiency of using hydrogen peroxide solutions for in situ indirect electrocatalytic oxidation of organic and inorganic substrates to target products (indirect electrochemical synthesis), for decomposition (mineralization) of organic and inorganic pollutants in industrial waters and wastewaters, and for preparation of organic peroxy acids and inorganic peroxy solvates.     

Effect of the thickness and porosity of carbon-black gas-diffusion air electrodes on the efficiency of hydrogen peroxide synthesis from atmospheric oxygen

Effect of the porosity and thickness of hydrophobized gas-diffusion air electrodes composed of A 437-E acetylene black or its mixture with P 702 and P 701 furnace blacks on the efficiency of electroreduction of atmospheric oxygen to H₂O₂ in 0.5 M NaOH was studied.     

Variation of the capacity characteristics of a composite material consisting of acetylene black and polytetrafluoroethylene and of its wettability with an aqueous solution under the action of anodic current

The effect exerted by treatment with cyclic anodic current in 1 M H₂SO₄ in the interval 0.0–2.0 V on electrodes made of a porous (55 vol %) composite material consisting of A-437E acetylene black and polytetrafluoroethylene (60 wt %) was studied. The cyclic volt–ampere curves were recorded in 3 M KOH and 1 M H₂SO₄ to determine the double layer capacity. The anodic treatment leads to an increase in the volume of pores filled with the electrolyte and in the electrical capacity of the electrode due both to an increase in the area of the surface wetted with the electrolyte and to the pseudocapacity caused by oxidation of the carbon black surface.     

The effect of dehydration on the position of cesium cations in the structure of CsNaFAU(Y) studied by powder X-ray diffraction and magic-angle spinning NMR spectroscopy

The influence of dehydration on the position of sodium and cesium cations obtained by ion exchange in the structure of FAU(Y) was studied by powder X-ray diffraction using synchrotron radiation and ²³Na and ¹³³Cs magic-angle spinning NMR spectroscopy. The sodium and cesium cations were found to be mobile in the hydrated samples. In dehydrated zeolites CsNaFAU(Y), cesium is predominantly localized in four crystallographic ion-exchange positions located in the large cavities and sodalite cages.     

Effect of the composition of gas-diffusion carbon black electrodes on electrosynthesis of hydrogen peroxide from atmospheric oxygen

Electroreduction of oxygen to H₂O₂ on gas-diffusion air electrodes made of A 437-E acetylene black and its mixture with P 702 and P 268-E furnace blacks with various particle sizes and wettabilities by an alkaline aqueous electrolyte with 8 and 20 wt % polytetrafluoroethylene was studied.     

Electrosynthesis of Н<Subscript>2</Subscript>О<Subscript>2</Subscript> from О<Subscript>2</Subscript> in a Gas-Diffusion Electrode Based on Mesostructured Carbon CMK-3

Mesostructured carbon CMK-3 (Carbon Mesostructured by KAIST) synthesized by the template method is studied as the electrocatalyst for electrosynthesis of Н₂О₂ from О₂ in a gas-diffusion electrode (GDE) in alkaline and acidic solutions. The texture characteristics of the original material and its mixture with hydrophobizer (polytetrafluoroethylene) are studied by the method of low-temperature nitrogen adsorption. The rate constants for hydrogen peroxide decomposition on these materials in alkaline and acidic solutions are calculated. Kinetic parameters of oxygen reduction in alkaline and acidic solutions are determined as well as the capacitance of gas-diffusion electrodes based on mesocarbon. The selectivity of the electrocatalyst is estimated by finding the current fracture γ consumed in oxygen reduction to hydrogen peroxide. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis of Н₂О₂ from О₂ are obtained. The acidic solution of hydrogen peroxide with the concentration more than 3 M is obtained with the current efficiency higher than 80%.     

Electrochemical reduction of oxygen in gas-diffusion electrodes based on expanded natural graphite

Electroreduction of oxygen in gas-diffusion hydrophobized porous electrodes containing 8–10 wt % fluoroplastic, made of expanded natural graphite and acetylene black, in acidic (pH 0.6) and alkaline electrolytes was studied.     

Effect of Electric Current on the Wettability of Carbon-Containing Gas Diffusion Electrodes by Aqueous Solutions and the Change in Their Capacitance Characteristics

Russian Journal of Electrochemistry - We study the effect of the treatment by an electric current of two-layer gas diffusion electrodes made of porous (66–68 vol %) composite material based...     

Double layer capacitance of gas-diffusion electrodes made of acetylene black and expanded natural graphites and evaluation of the surface area wetted by the electrolyte

Cyclic voltammetry was used to determine the capacitance of the double layer in hydrophobized porous gas-diffusion electrodes made of acetylene black and expanded natural graphites. The average radius of pores by with an alkaline electrolyte, the area of these pores, and the true current density in electro-reduction of oxygen were evaluated.