Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions

Thin passive films on tungsten play an important role during the surface levelling of the metal for various applications and during the initial stages of electrochemical synthesis of thick, nanoporous layers that perform well as photo-absorbers and photo-catalysts for light-assisted water splitting....

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Main Authors: Martin Bojinov, Yoanna Penkova, Iva Betova, Vasil Karastoyanov
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Metals
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Online Access:https://www.mdpi.com/2075-4701/14/9/1004
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author Martin Bojinov
Yoanna Penkova
Iva Betova
Vasil Karastoyanov
author_facet Martin Bojinov
Yoanna Penkova
Iva Betova
Vasil Karastoyanov
author_sort Martin Bojinov
collection DOAJ
description Thin passive films on tungsten play an important role during the surface levelling of the metal for various applications and during the initial stages of electrochemical synthesis of thick, nanoporous layers that perform well as photo-absorbers and photo-catalysts for light-assisted water splitting. In the present work, the passivation of tungsten featuring metal dissolution and thin oxide film formation is studied by a combination of in situ electrochemical (voltammetry and impedance spectroscopy) and spectro-electrochemical methods coupled with ex situ surface oxide characterization by XPS. Voltametric and impedance data are successfully reproduced by a kinetic model featuring oxide growth and dissolution coupled with the recombination of point defects, as well as a multistep tungsten dissolution reaction at the oxide/electrolyte interface. The model is in good agreement with the spectro-electrochemical data on soluble oxidation products and the surface chemical composition of the passive oxide.
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spelling doaj-art-db9dee2c49a343e6816248aa549eb34c2025-08-20T01:55:41ZengMDPI AGMetals2075-47012024-09-01149100410.3390/met14091004Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride SolutionsMartin Bojinov0Yoanna Penkova1Iva Betova2Vasil Karastoyanov3Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, BulgariaInstitute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia, BulgariaInstitute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia, BulgariaDepartment of Physical Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, BulgariaThin passive films on tungsten play an important role during the surface levelling of the metal for various applications and during the initial stages of electrochemical synthesis of thick, nanoporous layers that perform well as photo-absorbers and photo-catalysts for light-assisted water splitting. In the present work, the passivation of tungsten featuring metal dissolution and thin oxide film formation is studied by a combination of in situ electrochemical (voltammetry and impedance spectroscopy) and spectro-electrochemical methods coupled with ex situ surface oxide characterization by XPS. Voltametric and impedance data are successfully reproduced by a kinetic model featuring oxide growth and dissolution coupled with the recombination of point defects, as well as a multistep tungsten dissolution reaction at the oxide/electrolyte interface. The model is in good agreement with the spectro-electrochemical data on soluble oxidation products and the surface chemical composition of the passive oxide.https://www.mdpi.com/2075-4701/14/9/1004tungstenanodic oxidationprimary passivationelectrochemical impedance spectroscopyspectro-electrochemsitry
spellingShingle Martin Bojinov
Yoanna Penkova
Iva Betova
Vasil Karastoyanov
Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
Metals
tungsten
anodic oxidation
primary passivation
electrochemical impedance spectroscopy
spectro-electrochemsitry
title Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
title_full Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
title_fullStr Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
title_full_unstemmed Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
title_short Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions
title_sort mechanism of anodic dissolution of tungsten in sulfate fluoride solutions
topic tungsten
anodic oxidation
primary passivation
electrochemical impedance spectroscopy
spectro-electrochemsitry
url https://www.mdpi.com/2075-4701/14/9/1004
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AT vasilkarastoyanov mechanismofanodicdissolutionoftungsteninsulfatefluoridesolutions