Electrochemical behavior of sodium 12-tungstodicobaltoate in aqueous and mixed solvent electrolytes

Kasem, Kasem K.

doi:10.1016/0013-4686(95)00310-b

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…1,22 In general E 0 ′ values for polyoxometalates are highly dependent on the acidity, the polarity of the solvent and the concentration and identity of the supporting electrolyte. [23][24][25][26][27][28][29][30] Positive shifts in E 0 ′ have been reported in solvents with higher Lewis acidities and polarity. 18,[31][32][33] Thus, in a mixed CH 2 Cl 2 -CH 3 CN (80 : 20 v/v) solvent, the processes appear at a more negative potential (Fig.…”

Section: Resultsmentioning

confidence: 96%

Electrochemical probing of the photoreduction of molybdenum and tungsten Dawson-type polyoxometalates in molecular and ionic liquid media using water as an electron donor

et al. 2012

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The photochemistry of the Dawson-type [Bu(4)N](4)[S(2)Mo(18)O(62)] and [Bu(4)N](4)[S(2)W(18)O(62)] polyoxometalates in molecular solvents and [Bmim][BF(4)] and [Bmim][BF(6)] ionic liquids with water present as the electron donor is reported. Irradiation with UV (275-320 nm) or white (275-750 nm) light leads to reduction of the [S(2)Mo(18)O(62)](4-) anion and concomitant oxidation of water to give dioxygen and protons in all media examined. Oxygen gas also is rapidly evolved when solid [Bu(4)N](4)[S(2)Mo(18)O(62)] in contact with water is irradiated with light. In contrast, photoreduction of [S(2)W(18)O(62)](4-) is observed only in "wet" ionic liquids. Reactants and products associated with the photochemical reactions were monitored by a range of electrochemical methods. Substantial shifts in reversible potentials combined with modified structure of water introduced by water-IL interactions are hypothesised to facilitate photooxidation of water in ionic liquid environments. Intriguingly, whilst the polyoxotungstate is preferable as a photosensitizer, the molybdenum analogue is superior for photooxidation of water to dioxygen.

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Section: Resultsmentioning

confidence: 96%

Electrochemical probing of the photoreduction of molybdenum and tungsten Dawson-type polyoxometalates in molecular and ionic liquid media using water as an electron donor

et al. 2012

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“…According, HPA is reduced by a one-electron mechanism, and the redox process is quasi-reversible. 22,23 Two-Component System. Pd(OAc) 2 + BQ System.…”

Section: Resultsmentioning

confidence: 99%

“…The peak potential separation of the VO 2 + /VO 2+ couple is estimated to be 80 mV, and the redox peaks of the VO 2 + /VO 2+ couple roughly remain unchanged at various scan rates. According, HPA is reduced by a one-electron mechanism, and the redox process is quasi-reversible. , …”

Section: Resultsmentioning

confidence: 99%

Electrochemical Study on Palladium Acetate + p-Benzoquinone + Molybdovanadophosphate System by Cyclic Voltammetry

et al. 2009

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Palladium compounds + p-benzoquinone (BQ) + molybdovanadophosphate are of great interest in many catalytic reactions. The electrochemical characteristics of the palladium acetate + BQ + molybdovanadophosphate system in acid aqueous solution are studied by cyclic voltammetry. The redox process of palladium species involves a two-electron reaction, which can be expressed as Pd 2+ + 2e T Pd 0 . Since both BQ and molybdovanadophosphate can reoxidize Pd 0 to Pd 2+ , an appropriate amount of BQ or molybdovanadophosphate can enhance the catalytic activity of Pd 2+ and the oxidative reaction rate. However, excessive BQ or molybdovanadophosphate decreases the reaction rate. Since molybdovanadophosphate can reoxidize the reduced form of BQ, adding an appropriate amount of molybdovanadophosphate to the Pd 2+ + BQ system enhances the catalytic activity of Pd 2+ . The injection of oxygen to Pd 2+ + BQ + molybdovanadophosphate system can increase the oxidative reaction rate of molybdovanadophosphate and ultimately enhance the activity of Pd 2+ .

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“…[28][29][30] For example, the electrochemical behaviour of [Co2W12O42] 8was found to be highly solvent dependent. [31] The reversible potentials associated with these Wbased redox centres shift negatively in a 50% mixed solvent aqueous electrolyte of dimethylformamide/water, acetonitrile/water or acetone/water compared to a pure aqueous electrolyte solution, while in dioxane/water mixtures, the processes shifted positively. The acidity of the media (proton availability) also influences the thermodynamic properties of POMs.…”

Section: Introductionmentioning

confidence: 99%

Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3–/4– (VV/IV) and [SVW11O40]4–/5– (WVI/V) processes in propylene carbonate

Bentley

Ueda

et al. 2018

Journal of Electroanalytical Chemistry

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Changing the supporting electrolyte cation from tetrabutylammonium to 1-butyl-3methylimidazolium is known to significantly increase the apparent heterogeneous electron transfer rate constants ( 0 value at the formal reversible potential ( 0 )) associated with the [SVW11O40] 3−/4− (V V/IV ) and [SVW11O40] 4−/5− (W VI/V ) processes in aprotic organic media. In this study, supporting electrolytes containing 7 different cations, namely 1-ethyl-3methylimidazolium ([EMIM] + ), 1-butyl-3-methylimidazolium ([BMIM] + ), 1-butyl-1methylpyrrolidinium ([Py14] + ), tetraethylammonium ([TEA] + ), tetrapropylammonium ([TPA] + ), tetrabutylammonium ([TBA] + ) and tetrahexylammonium ([THA] + ), have been investigated in order provide a systematic account of the influence of electrolyte cations on the rate of polyoxometalate (POM) electron transfer at a platinum disk electrode. Fourier transformed alternating current (FTAC) voltammetry has been used for the measurement of fast kinetics and DC cyclic voltammetry for slow processes. The new data reveal the formal reversible potentials and electron-transfer rate constants associated with the V V/IV ( V 0 ) and W VI/V ( W 0 ) processes correlate with the size of the supporting electrolyte cation. V 0 and W 0 values decrease in the order, [EMIM] + > [BMIM] + > [Py14] + ≈ [TEA] + > [TPA] + > [TBA] + > [THA] + for both processes. However, while V 0 decreases gently with increasing cation size (k 0 = 0.1 and 0.002 cm s -1 with [EMIM] + and [THA] + electrolyte cations, respectively), the decrease in W 0 is much more drastic (k 0 = 0.1 and 2 × 10 -6 cm s -1 for [EMIM] + and [THA] + , respectively). Possible explanations for the observed trends are discussed (e.g., ion-pairing, viscosity, adsorption and the double-layer effect), with inhibition of electron-transfer by a blocking "film" of electrolyte cations considered likely to be the dominant factor, supported by a linear plot of ln(k 0 ) vs. ln(d) (where d is the estimated thickness of the adsorbed layer on the electrode surface) for both the V V/IV and W VI/V processes.

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Electrochemical behavior of sodium 12-tungstodicobaltoate in aqueous and mixed solvent electrolytes

Cited by 11 publications

References 22 publications

Electrochemical probing of the photoreduction of molybdenum and tungsten Dawson-type polyoxometalates in molecular and ionic liquid media using water as an electron donor

Electrochemical probing of the photoreduction of molybdenum and tungsten Dawson-type polyoxometalates in molecular and ionic liquid media using water as an electron donor

Electrochemical Study on Palladium Acetate + p-Benzoquinone + Molybdovanadophosphate System by Cyclic Voltammetry

Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3–/4– (VV/IV) and [SVW11O40]4–/5– (WVI/V) processes in propylene carbonate

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