Oxygen Reduction In Aqueous Solutions Research Articles

Single entity electrocatalysis: oxygen reduction mediated via methyl viologen doped Nafion nanoparticles.

Nafion particles doped with methyl viologen are shown to be electrocatalytic towards oxygen reduction in aqueous solution when immobilised on a carbon electrode surface, with the formation of hydrogen peroxide. In this way an efficient homogeneous electron transfer mediator, methyl viologen, can be confined to act heterogeneously with the benefits of that type of process without losing effectiveness. Kinetic and mechanistic parameters are deduced from cyclic voltammetry and from single entity nano-impact experiments, and the process is shown to occur via electron transfer to dioxygen at the Nafion particle-solution interface with the initial formation of superoxide.

Electrochemical Characterization of Catalytic Activities of C60 Nanowhiskers to Oxygen Reduction in Aqueous Solution

We have investigated the catalytic function and activity of C60 nanowhiskers (C60NWs) on glassy carbon electrodes to the electrochemical O2 reduction in aqueous solution by cyclic voltammetry. It is found that C60NWs are active catalysts for O2 reduction in aqueous solution, although pristine C60 powders do not show any activities. The porous and conductive features of C60NWs play important roles in the electrochemical O2 reduction.

Composite Catalysts towards Oxygen Reduction in Aqueous Solutions

Electrochemical properties and possibilities of manufacturing the anodes based on water-soluble binders such as carboxymethylcellulose (CMC) have been investigated in order to create prerequisites for development of “green” technologies for recyclability of LIBs components.In this work an advanced anode was designed. A kind of nanosized carbon coated Si composite was synthesized. The charge/discharge test reveals that the advanced anode shows a reversible capacity of 600 mAh/g. The improved performance was ascribed to the carbon shell of Si and CMC binder. The binder CMC buffers the expansion of the Si and the improved electric contact between the active material and copper current collector.

Four-Electron Oxygen Reduction by Brominated Cobalt Corrole

The carbon-supported cobalt(III) complex of β-pyrrole-brominated 5,10,15-tris(pentafluorophenyl)corrole [Co(tpfc)Br(8)/C] is introduced as a nonplatinum alternative for electrocatalytic oxygen reduction in aqueous solutions. Through systematic work, the basic kinetic parameters of this reaction were studied, using rotating ring disk electrode electrochemical methods in the pH range of 0-11. Pronounced catalytic activity was detected in acid solutions along with shifts of the Co(II)/Co(III) and O(2) redox couples to more positive values (onset of 0.56 V at pH 0). A series of independent measurements have been used to prove that the dominant mechanism for oxygen reduction by Co(tpfc)Br(8)/C catalysis is the direct four-electron pathway to water.

Electrochemical Behaviors for Conductive Porous Alumina Composites with Gelcast-Derived Nanocarbon Networks in Aqueous Solutions

A novel, highly conductive porous alumina/nanocarbon network (alumina/NCN) composites were fabricated. The electrochemical behaviors of the composite materials were studied by electrochemical measurements, X-ray diffraction patterns, scanning electron microscopy observations, and so on. The results showed that the reproducibility and stability of the fabricated nanocarbon composites are good enough for use as electrodes in strong acidic and alkaline environments. The fabricated electrode in electrochemical performances was to some extent closer to graphite electrode rather than glassy carbon in these aqueous solutions. The porous nanocarbon electrodes seemed to have certain electrocatalysis capabilities for hydrogen evolution or oxygen reduction in aqueous solutions. These performances are attributed to the existence of pyrolyzed NCN derived from polymer and its high porosity in the composite matrix. The possible cathodic and anodic electrode reactions on this nanocarbon electrode surface were proposed and discussed according to their standard potentials reported in the literature. In addition, alumina particles or grain boundary phase dissolution in the electrode was a simple hydrolysis reaction with very low dissolution rate at ambient conditions, which did not involve the electrode reactions.

Polarographic study of the antioxidant activity of amino acids and proteins

Classical polarography and cyclic voltammetry were used to study the effect of a series of water-soluble amino acids and serum albumins on oxygen reduction in aqueous solutions. Positive or negative shifts of the reduction potential of oxygen were revealed, depending the nature of the compounds. The feasibility of polarographic methods for studying antioxidant properties of compounds was demonstrated.

Deoxygenation of Aqueous Solutions by Cathodically Polarized Copper-Containing Redox Cation Exchanger

Oxygen reduction in aqueous solutions by cathodically polarized copper-containing redox resins was studied. To provide reagent-free, continuous, and exhaustive deoxygenation, the rate of surface electroless oxidation with oxygen should be equal to the rate of electrochemical reduction (regeneration) of the redox centers.

Oxygen Reduction on Pyrolytic Graphite Electrodes Modified with Electropolymerized Cobalt Salen Compounds

Electropolymerized cobalt salen compounds on pyrolytic graphite electrodes were first tested as oxygen reduction catalysts in aqueous solutions of various pH. N,N′‐Bis(salicylidene)ethylenediaminocobalt(II) [abbreviated Co(salen)] and its analogs were polymerized on a basal plane of pyrolytic graphite electrode by electrochemical polarization from deaerated acetonitrile solutions. The cyclic voltammetry of Co(salen) modified electrodes showed that electropolymerized Co(salen) effectively catalyzed oxygen reduction in aqueous solutions, and features such as half‐wave potentials or limiting current density of oxygen reduction were satisfactory as compared with those of cobalt porphyrin‐modified electrodes. The characteristics of oxygen reduction catalyzed by electropolymerized Co(salen) were investigated using rotating ring‐disk electrode measurements in acidic, neutral, and basic solutions. The efficiency of four‐electron reduction of oxygen was found to be best in basic solutions. The results revealed that although in acidic media the catalyst performance deteriorated in a short time, the performance in neutral and basic media was relatively good as compared with that of platinum, the best catalyst for this reaction. © 1999 The Electrochemical Society. All rights reserved.