In-situ Moessbauer study of redox processes in a composite hydroxide of iron and nickel

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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“…Nevertheless, nickel is also detected in the surface layers (see Fig. 3, Table 2), which refutes assumption (1).…”

Section: Resultssupporting

confidence: 80%

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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“…81,82 The authors proposed that enhancement of the OER could be brought about via a partialcharge transfer activation effect on Ni mediated by Fe. Noting that increasing the Fe content of NiFe-oxide films pushes the Ni(II)/Ni(III) couple to more anodic potentials (see similar arguments advanced by Bell, above), and that partial-charge transfer between Fe and Ni 3+/4+ was previously proposed by Corrigan, 84 the authors reasoned that adding Fe would therefore make it more difficult to oxidise the Ni(II) centres in the film and thus produce Ni 3+/4+ species with more oxidizing power and possibly enhanced OER activity. This work has been extended recently to include nickel oxide electrodeposits obtained from borate buffers at near neutral pH (similar conditions to those employed by Nocera and co-workers with their NiBi catalyst, see Section 4).…”

Section: Electrodeposited Catalysts For Water Oxidation Based On Mixementioning

confidence: 55%

First row transition metal catalysts for solar-driven water oxidation produced by electrodeposition

Roger

Symes

2016

J. Mater. Chem. A

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There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/114759/ Isolda Roger and Mark D. Symes* As our reliance on renewable energy resources increases, so will our need to store this energy in the form of chemical fuels to iron-out peaks and troughs in supply. Sunlight, the most plentiful source of renewable energy, is especially problematic in this regard as it is so diffuse. One way to convert solar irradiation to fuels effectively would be to develop large surface area photo-electrochemical devices that could use sunlight directly to split water into H2 and O2. However, in order to be feasible, such an approach requires that these devices (and their components) are extremely cheap. In this review, we will discuss catalysts for the water oxidation half-reaction of electrochemical water splitting that can be produced by electrodeposition (a technique well suited to large-scale, low-cost applications), and that are based on the comparatively plentiful and inexpensive first row transition metals. Special attention will be paid to the electrodeposition conditions used in the various examples given, and structure-function relationships for electrochemical water oxidation for the materials produced by these techniques will be elucidated.

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“…[19][20][21] Among the most active and investigated OER electrocatalysts in basic electrolytes are transition metal oxy hydroxides. [22][23][24][25][26][27] Their high activity is ascribed in part to volume activity of the hydrated catalyst. However, the role of adventitious iron contamination [28][29][30][31] and their behavior as "adaptive junctions", 32,33 i.e.…”

Section: Introductionmentioning

confidence: 99%

An Operando Investigation of (Ni–Fe–Co–Ce)O_x System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction

et al. 2017

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Abstract. The oxygen evolution reaction (OER) is a critical component of industrial processes such as electrowinning of metals and the chlor-alkali process. It also plays a central role in the developing renewable energy field of solar-fuels generation by providing both the protons and electrons needed to generate fuels such as H 2 or reduced hydrocarbons from CO 2 . To improve these processes, it is necessary to expand the fundamental understanding of catalytically active species at low overpotential, which will further the development of electrocatalysts with high activity and durability. In this context, performing experimental investigations of the electrocatalysts under realistic working regimes, i.e. under operando conditions, is of crucial importance. Here, we study a highly active quinary transition metal oxide-based OER electrocatalyst by means of operando ambient pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy performed at the solid/liquid interface. We observe that the catalyst undergoes a clear chemical-structural evolution as a function of the applied potential with Ni, Fe and Co oxyhydroxides comprising the active catalytic species. While CeO 2 is redox inactive under catalytic conditions, its influence on the redox processes of the transition metals boosts the catalytic activity at low overpotentials, introducing an important design principle for the optimization of electrocatalysts and tailoring of high performance materials.

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In-situ Moessbauer study of redox processes in a composite hydroxide of iron and nickel

Cited by 111 publications

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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

First row transition metal catalysts for solar-driven water oxidation produced by electrodeposition

An Operando Investigation of (Ni–Fe–Co–Ce)O_x System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction

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In-situ Moessbauer study of redox processes in a composite hydroxide of iron and nickel

Cited by 111 publications

References 1 publication

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

First row transition metal catalysts for solar-driven water oxidation produced by electrodeposition

An Operando Investigation of (Ni–Fe–Co–Ce)Ox System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction

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An Operando Investigation of (Ni–Fe–Co–Ce)O_x System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction