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Electrochemical impedance spectroscopic studies on niobium anodic dissolution in HF
Published in Springer New York LLC
2017
Volume: 21
   
Issue: 11
Pages: 3155 - 3167
Abstract
The dissolution of niobium electrode in anodic regime in hydrofluoric acid was studied using electrochemical techniques. In the active region, complex plane plots of the impedance spectra exhibited mainly two capacitive loops. In the passive region, the spectra exhibited a mid-frequency pseudo-inductive loop and a low-frequency negative resistance. X-ray photoelectron spectroscopic analysis showed that the surface contains Nb2+ and Nb5+. The impedance data were analysed using equivalent circuit with Maxwell elements as well as mechanistic modelling. A four-step mechanism with a chemical and electrochemical dissolution step is proposed to explain the results. The results show that Nb with an oxidation state of 2 is likely to be an intermediates species. The simulations predict that at low over potentials, the surface is covered mainly with bare metal, whereas at high over potentials, the surface is entirely covered by passivating Nb5+ film. © 2017, Springer-Verlag Berlin Heidelberg.
About the journal
JournalData powered by TypesetJournal of Solid State Electrochemistry
PublisherData powered by TypesetSpringer New York LLC
ISSN14328488
Open AccessNo
Concepts (15)
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    Dissolution
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    Equivalent circuits
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    Hydrofluoric acid
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    Reaction intermediates
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    Spectroscopic analysis
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    X ray photoelectron spectroscopy
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    Anodic dissolution
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    ELECTROCHEMICAL DISSOLUTION
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    Electrochemical impedance
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    Electrochemical techniques
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    Impedance spectrum
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    MECHANISTIC ANALYSIS
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    Spectroscopic studies
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    X-ray photoelectrons
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    Niobium