Voltammetric and spectroelectrochemical studies of dodecamolybdophosphoric acid in aqueous and water-dioxane solutions at a gold-minigrid optically transparent thin-layer electrode

Tanaka, Nobuyuki; Unoura, Kei; Itabashi, Eiki

doi:10.1021/ic00134a077

Cited by 36 publications

(31 citation statements)

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“…Figure 2 shows the cyclic voltammetric response of PMO,~O,,~-at a bare GC electrode in dioxane-water solution containing 0.5 M H2S04 and after incorporation in a polyRu(vbpy), ,+and PVP films from the same medium. The homogeneous solution response of PMo,, agrees with the previously reported behavior of this compound (15,(18)(19)(20) and consists of a series of chemically reversible two-electron reductions, which occur at +0.37, +0.25 , -0.02, -0.16, and -0.25 V vs. AgIAgC1. Figures 2B and 2C and Table 2 show that some changes in PMo,, electrochemistry occur after incorporation in poly-~u(vbpy)32+ and PVP.…”

Section: Effect Of Solution and Polymer Environment On Redox Propertisupporting

confidence: 89%

“…They have been widely studied as catalysts of thermal (5-7) and photochemical (8)(9)(10) reactions and as models for catalytic reactions at metal oxide surfaces (1 1). Although the electrochemistry of polyoxometalates has been investigated for several decades (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25), exploitation of their catalytic properties in electrochemical reactions has begun only recently. Polyoxometalates should be excellent electrocatalysts because of their chemical stability and capacity to undergo multielectron charge transfer reactions.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemistry of polyoxometalates immobilized in ion exchange polymer films

Kasem¹,

Schultz²

1995

Can. J. Chem.

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Abstract:The polyoxometalate ions P M O , ,~, ,~~, PW~,O,~-, and S~W,,O,;-are incorporated in polymeric ruthenium(II)(vinyl)bipyridine (poly-~u(vbpy),2+) films from aqueous and dioxane-water electrolytes. Despite their large mass the ions exist as freely diffusing species that compensate for up to 30% of the chage in poly~u ( v b~~)~~~. An investigation of the effect of environmental conditions on electrochemical behavior reveals that the first two one-electron reduction waves of s~w,,o,,~-coalesce into a single two-electron reaction and those of PW,,O,,,-shift significantly in potential upon a change from pure aqueous to 50(v/v)% dioxanelwater solvent. The observation is attributed to destabilization of the one-electron reaction products as the solvent is enriched is dioxane. Incorporation of polyoxometalates in protonated poly(viny1)pyridine and poly~u ( v b~~) ,~~ films from dioxane-water solvent results in differences in electrochemical behavior. Polyoxometalate anions incorporated in poly-~u(vbpy)3'f films catalyze the electrochemical reduction of hydrogen ion.Key words: polyoxometalate, electrochemistry, poly-~u(vbpy)32+, electrocatalysis, immobilization.RCsumC : On a incorporC les ions polyoxomCtallates PMO,~~,,", PW,,~,," et Siwl,O4,4-dans des films polymCriques de mthCnium(II)(vinyl)bipyridine (poly-~u(vbpy),") 2 partir d'Clectrolytes en solutions dans l'eau ou dans un mClange eau~lioxane. MalgrC leurs masses importantes, les ions existent sous la forme d'espkces qui diffusent librement et ils peuvent compenser Clectrostatiquement jusqu'i 30% de la chage du poly-~u(vbpy)33+. Une Ctude de l'effet des conditions environnementales sur le comportement Clectrochimique rCvkle que le potentiel des deux premikres vagues de rCduction du s~w ,~o , ,~-par un Clectron est fortement modifiC lorsqu'on passe de I'eau pure i un mClange de solvants form6 i 50% (vlv) de dioxaneleau. On attribue ces observations i la destabilisation des produits de rCduction par un Clectron lorsqu'on enrichit le solvant en dioxane. L'incorporation de polyoxomCtallates dans des films de poly(viny1)pyridine ou de poly~u ( v b~~) ,~+ protonCs B partir de solvants mixtes dioxane-eau provoque des diffkrences dans le comportement Clectrochimique. Les anions polyoxomCtallates incorporCs dans les films de poly-~u(vbpy)33f catalysent la rCduction Clectrochimique de l'ion hydrogkne.

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Section: Effect Of Solution and Polymer Environment On Redox Propertisupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Electrochemistry of polyoxometalates immobilized in ion exchange polymer films

Kasem¹,

Schultz²

1995

Can. J. Chem.

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“…In fact, the correlation between the anionic charge of 12-MPA and its first reduction potential is linear [38,43]. Voltammetric analysis of 12-MPA in aqueous 0.2 mol L À1 H 2 SO 4 solutions (pH z 0.78) has shown that 12-MPA may undergo two successive and reversible two-electron reductions at þ0.31 V and þ0.17 V [42], which decrease to þ0.27 V and þ0.13 V at pH 1 [44]. A third two-electron reduction at about À0.08 V is possible but this renders the product highly unstable, resulting in immediate decomposition [42] (Fig.…”

Section: Reduction Of 12-mpamentioning

confidence: 99%

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

Nagul

McKelvie

Worsfold

et al. 2015

Analytica Chimica Acta

340

247

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The molybdenum blue reaction, used predominantly for the determination of orthophosphate in environmental waters, has been perpetually modified and re-optimised over the years, but this important reaction in analytical chemistry is usually treated as something of a 'black box' in the analytical literature. A large number of papers describe a wide variety of reaction conditions and apparently different products (as determined by UV-visible spectroscopy) but a discussion of the chemistry underlying this behaviour is often addressed superficially or not at all. This review aims to rationalise the findings of the many 'optimised' molybdenum blue methods in the literature, mainly for environmental waters, in terms of the underlying polyoxometallate chemistry and offers suggestions for the further enhancement of this time-honoured analytical reaction.

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“…It has been reported in the literature that the complexes of phosphate and silicate with molybdenum have simpler electrochemistry in aqueous/organic solvent mixtures [15][16][17]. Voltammograms were therefore recorded for both silicate and phosphate in an acetone/water medium prepared by mixing equal volumes of acetone and a solution of 10 mM molybdate in water adjusted to pH 1.4 by the addition of hydrochloric acid.…”

Section: Organic Solvents and Complexing Agentsmentioning

confidence: 99%

Microelectrode Procedures for the Analysis of Silicate and Phosphate — Towards Practical Procedures

Hodgson

Pletcher

1998

Electroanalysis

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Amperometric methods using microdisk electrodes and based on the formation of electroactive molybdophosphate and molybdosilicate complexes are described for the determination in water samples of phosphate and silicate. It is demonstrated that it is possible to devise conditions for the analysis of 1-100 mM phosphate or silicate in the presence of a large excess of the other. It is also possible to determine both phosphate and silicate in a single analysis provided they are present in not too dissimilar concentrations.

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Voltammetric and spectroelectrochemical studies of dodecamolybdophosphoric acid in aqueous and water-dioxane solutions at a gold-minigrid optically transparent thin-layer electrode

Cited by 36 publications

References 0 publications

Electrochemistry of polyoxometalates immobilized in ion exchange polymer films

Electrochemistry of polyoxometalates immobilized in ion exchange polymer films

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

Microelectrode Procedures for the Analysis of Silicate and Phosphate — Towards Practical Procedures

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