Mössbauer spectroscopic study of ferric hydroxo complexes adsorbed at nickel hydroxides from strongly alkaline electrolytes

Kamnev, Alexander A.; Ezhov, B. B.; Rusanov, V.; Angelov, V.

doi:10.1016/0013-4686(92)87038-2

Cited by 13 publications

(3 citation statements)

References 16 publications

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“…Some other details of Mossbauer experimental procedure concerning sample preparation, apparatus, spectra acquisition and data treatment have been thoroughly described elsewhere. [20][21][22] To perform AES analyses, samples of binary hydroxide powders were carefully pressed into an indium metal platelet and attached to the spectrometer holder. The starting pressure of residual gases in the analysis chamber was 5 x lo-' Pa.…”

Section: Methodsmentioning

confidence: 99%

Application of transmission Mössbauer spectroscopy to the surface study of Ni(II)–Fe(III) hydroxide electrocatalysts: Comparison with AES data

Kamnev

Angelov

Smekhnov

1993

Surface & Interface Analysis

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Transmission Mossbauer spectra of binary coprecipitated nickel(I1)-iron(II1) hydroxides (molar ratios 9 : 1 and 4:l) are analysed and compared with the results of AES analyses of their surface composition. A correlation between the data of the above techniques has been noted, indicating a redistribution of the components (i.e. Ni and Fe) in the surface layers, the latter being enriched with iron(1II) as compared to the bulk. The results obtained are in good agreement with an excellent electrocatalytic activity of composite Ni-Fe hydroxide systems towards anodic oxygen evolution in alkaline electrolytes, taking into account a distinctly exhibited 'surface' electrocatalytic effect of ferric species on the nickel hydroxide electrode in the anodic oxygen evolulion process revealed previously. Transmission Miissbauer spectroscopy has been shown to be a highly effective prob sensitive both to various bulk and surface effects related to the solid phases studied.

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Section: Methodsmentioning

confidence: 99%

Application of transmission Mössbauer spectroscopy to the surface study of Ni(II)–Fe(III) hydroxide electrocatalysts: Comparison with AES data

Kamnev

Angelov

Smekhnov

1993

Surface & Interface Analysis

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“…27 Upon heating, the symmetry of the complex was retained and the observed increase in the line width was attributed to the non-uniformity of the complexes' environment due to non-uniform drying. 28 The colloidal and/or polynuclear complex (during a 3.5 years ageing period) was found to transform to a reddish-brown solid complex with M össbauer spectral parameters very similar to those of the solid obtained upon evaporation. 29 From this, Kamnev et al concluded that (in accordance with their UV-vis observations 10,11 obtained for solutions) the species responsible for the unique M össbauer spectrum is most likely to be built up from [Fe(OH) 4 ]units in the solid state.…”

Section: Introductionmentioning

confidence: 88%

“…For example, a number of solid complexes either with [M(OH) 4 ]or with [M(OH) 6 ] 3-(M = Al(III) and Ga(III)) building blocks are known from the literature, 24-26 but in the solutions from which these complexes are obtained, neither [Al(OH) 6 ] 3nor [Ga(OH) 6 ] 3are present in experimentally detectable quantities. 5, 8 Kamnev et al made a remarkable effort [27][28][29] to elucidate the M össbauer spectrum of the Fe(III)-hydroxo complex species forming in strongly alkaline aqueous solutions. In concentrated (15-17 M) NaOH solution, ferric ions were found to form a reddishorange (supposedly colloidal and/or polynuclear) compound.…”

Section: Introductionmentioning

confidence: 99%

The structure of Fe(iii) ions in strongly alkaline aqueous solutions from EXAFS and Mössbauer spectroscopy

et al. 2008

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To establish the structure of ferric ions in strongly alkaline (pH > 13) environments, aqueous NaOH solutions supersaturated with respect to Fe(III) and the solid ferric-hydroxo complex salts precipitating from them have been characterized with a variety of experimental techniques. From UV measurements, in solutions of pH > 13, only one kind of Fe(III)-hydroxo complex species was found to be present. The micro crystals obtained from such solutions were proven to be a new, so far unidentified solid phase. Mössbauer spectra of the quick-frozen solution and that of the complex salt indicated a highly symmetrical ferric environment in both systems From the EXAFS and XANES spectra, the environment of the ferric ion in these solutions (both native and quick-frozen) and in the complex salt was found to be different. In the complex salt, the bond lengths are consistent with an octahedral coordination around the ferric centres. In solution, the coordination geometry of Fe(III) is most probably tetrahedral. Our results demonstrate that in strongly alkaline aqueous solutions, ferric ions behave very similarly to other structurally related tervalent ions, like Al(III) or Ga(III).

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Application of transmission Mössbauer effect spectroscopy to the study of electrocatalysis and adsorption phenomena at the nickel hydroxide electrode

Kamnev

Ezhov

Rusanov

et al. 1992

Surface & Interface Analysis

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Miissbauer parameters for ferric hydroxo forms in alkaline matrices, ferric oxyhydroxide and its admixture at the nickel hydroxide electrode surface as well as for ferric hydroxo species adsorbed at nickel hydroxides from strongly alkaline solutions have been compared. The feasibility of transmission Miissbauer spectra acquisition for the adsorbed species in the presence of dissolved forms (e.g. in sir#) is based on the principle that the latter give no Miissbauer effect at room temperature owing to their diffusional mobility, while the former, being fixed at the adsorbent surface, have been shown to exhibit a sufiicient resonant absorption. Tbe effects of adsorption and adsorbent surface state on the coordination of ferric hydroxo complexes as well as its hydrolytic destruction in water have been noted. Some questions connected with anodic oxygen evolution electrocatalysis by iron species involved in the anodic process at the nickel hydroxide electrode are also discussed.

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Mössbauer spectroscopic study of ferric hydroxo complexes adsorbed at nickel hydroxides from strongly alkaline electrolytes

Cited by 13 publications

References 16 publications

Application of transmission Mössbauer spectroscopy to the surface study of Ni(II)–Fe(III) hydroxide electrocatalysts: Comparison with AES data

Application of transmission Mössbauer spectroscopy to the surface study of Ni(II)–Fe(III) hydroxide electrocatalysts: Comparison with AES data

The structure of Fe(iii) ions in strongly alkaline aqueous solutions from EXAFS and Mössbauer spectroscopy

Application of transmission Mössbauer effect spectroscopy to the study of electrocatalysis and adsorption phenomena at the nickel hydroxide electrode

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