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Redox

About: Redox is a research topic. Over the lifetime, 26853 publications have been published within this topic receiving 862368 citations. The topic is also known as: reduction-oxidation & reduction-oxidation reaction.


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Journal ArticleDOI
TL;DR: In this article, the electrochemical behavior of a bismuth surface compound formed spontaneously without applying external potential when platinum is put in contact with a solution of a Bi(III) salt was studied.

253 citations

Journal ArticleDOI
TL;DR: In this paper, a vertical advection-diffusion model was used to study the distribution of dissolved manganese, copper, iron, and zinc in the Black Sea basin and showed that the distributions of these elements are markedly affected by redox reactions at the boundary between oxygenated surface waters and the sulfide-containing deep waters.
Abstract: Profiles of dissolved manganese, copper, iron, and zinc show that the distributions of these elements are markedly affected by redox reactions at the boundary between oxygenated surface waters and the sulfide-containing deep waters. Copper and zinc are depleted in the deep water by precipitation as insoluble sulfides. The concentrations of manganese and iron in the deep water greatly exceed those of the surface water principally because of the greater solubility of the sulfides and hydroxides of the reduced species as compared with the solubility of hydroxides and oxides of the oxidized species. The distribution of dissolved nickel and cobalt does not appear to be greatly affected by redox reactions. The profile of dissolved manganese, which shows a pronounced mid-water maximum about 40 meters below the oxygen zero boundary, has been explained with the aid of a vertical advection-diffusion model. We suggest that the Black Sea basin is currently acting as a very efficient trap for manganese. A flux of manganese, from surface particulates, of about 200 mg m−2 year−1, which is reduced and dissolved immediately upon penetrating to the sulfide-containing waters, builds up a mid-water maximum until the concentration gradient between the maximum and the deep water is sufficient to drive an equivalent diffusive flux of manganese into the deep water. Manganese is not lost by upward diffusion and advection because the reduced species is oxidized and precipitated just above the oxygen zero boundary and hence adds to the total flux of particulate manganese into the deep water. Currently the total flux of particulate manganese that is going into solution in the deep water is about 875 mg m−2 year−1 of which 675 mg m−2 year−1 is derived from the precipitation of dissolved manganese. The latter amount will increase in the future until the concentration of dissolved manganese at the midwater maximum exceeds the solubility product of some salt. Although we have performed no calculations, the shape of the dissolved iron profile indicates that a mechanism similar to that described for manganese is controlling the distribution. In addition it is likely that sulfide precipitation limits the iron concentration in the deep water.

253 citations

Journal ArticleDOI
TL;DR: In this paper, the known complex {Cp(PPh3)2Ru}2(μ-C⋮CC⋫C) (3-Me) has been shown by cyclic voltammetry to undergo a series of four stepwise one-electron oxidation processes.
Abstract: The known complex {Cp(PPh3)2Ru}2(μ-C⋮CC⋮C) (3-Ph) and its PMe3-substitution product {Cp(PPh3)(PMe3)Ru}2(μ-C⋮CC⋮C) (3-Me) have been shown by cyclic voltammetry to undergo a series of four stepwise one-electron oxidation processes. Successive oxidation potentials (V) for the first three reversible processes of 3-Ph (3-Me) are −0.23 (−0.26), +0.41 (+0.33), and +1.03 (+0.97); the fourth, irreversible oxidation at +1.68 (+1.46) V is accompanied by chemical transformation followed by further oxidation. Chemical oxidation of 3-Ph with 1 or 2.5 equiv of AgPF6 in CH2Cl2/1,2-dimethoxyethane gave the one- and two-electron oxidized species [3-Ph][PF6] and [3-Ph][PF6]2, respectively. The chemical and electrochemical studies have been complemented by a series of detailed spectroelectrochemical experiments to obtain spectral data associated with the 3n+ (n = 0−4) species from 1500 to 40 000 cm-1, without necessitating the isolation of each individual species. Theoretical techniques have been employed in order to probe t...

252 citations

Journal ArticleDOI
TL;DR: These insights establish a point defect explanation for why anion redox often occurs alongside local structural disordering and voltage hysteresis during cycling, and offer an explanation for the unique electrochemical properties of lithium-rich layered oxides.
Abstract: Reversible high-voltage redox chemistry is an essential component of many electrochemical technologies, from (electro)catalysts to lithium-ion batteries. Oxygen-anion redox has garnered intense interest for such applications, particularly lithium-ion batteries, as it offers substantial redox capacity at more than 4 V versus Li/Li+ in a variety of oxide materials. However, oxidation of oxygen is almost universally correlated with irreversible local structural transformations, voltage hysteresis and voltage fade, which currently preclude its widespread use. By comprehensively studying the Li2−xIr1−ySnyO3 model system, which exhibits tunable oxidation state and structural evolution with y upon cycling, we reveal that this structure–redox coupling arises from the local stabilization of short approximately 1.8 A metal–oxygen π bonds and approximately 1.4 A O–O dimers during oxygen redox, which occurs in Li2−xIr1−ySnyO3 through ligand-to-metal charge transfer. Crucially, formation of these oxidized oxygen species necessitates the decoordination of oxygen to a single covalent bonding partner through formation of vacancies at neighbouring cation sites, driving cation disorder. These insights establish a point-defect explanation for why anion redox often occurs alongside local structural disordering and voltage hysteresis during cycling. Our findings offer an explanation for the unique electrochemical properties of lithium-rich layered oxides, with implications generally for the design of materials employing oxygen redox chemistry. Reversible high-voltage redox is a key component for electrochemical technologies from electrocatalysts to lithium-ion batteries. A point defect explanation for why anion redox occurs with local structural disordering and voltage hysteresis is proposed.

252 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20233,178
20225,931
20211,509
20201,274
20191,219