Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes
The electrochemical oxidation of VO2+ at planar glassy carbon electrodes is investigated via stationary and rotating linear sweep voltammetry as well as via chronoamperometry. It is demonstrated that introducing finite kinetic rate constants into the Butler-Volmer equation captures the experimentall...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2020-10-01
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| Series: | Frontiers in Energy Research |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fenrg.2020.00155/full |
| _version_ | 1819162581046132736 |
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| author | Tim Tichter Jonathan Schneider Christina Roth |
| author_facet | Tim Tichter Jonathan Schneider Christina Roth |
| author_sort | Tim Tichter |
| collection | DOAJ |
| description | The electrochemical oxidation of VO2+ at planar glassy carbon electrodes is investigated via stationary and rotating linear sweep voltammetry as well as via chronoamperometry. It is demonstrated that introducing finite kinetic rate constants into the Butler-Volmer equation captures the experimentally observed concentration dependence of the ordinate intercept in Koutecký-Levich plots that cannot be explained by using the classical model. This new concept leads to a three-term Koutecký-Levich equation considering mass transport limitations, Butler-Volmer kinetics, as well as finite heterogeneous kinetics simultaneously. Based on these findings it is pointed out that stationary linear sweep voltammetry followed by an irreversible Randles-Ševčík analysis is not sufficient for deducing the electrode kinetics of the VO2+-oxidation. In contrast, it is verified experimentally and theoretically that a Tafel analysis will still provide reasonable values of k0 = 1.35 · 10−5 cm/s and α = 0.38, respectively. Finally, it is shown that introducing the concept of finite heterogeneous kinetics into the theory of stationary linear sweep voltammetry also explains the failure of the irreversible Randles-Ševčík relation leading to an extension of the classical model and providing insight into the electrochemical oxidation reaction of VO2+. |
| first_indexed | 2024-12-22T17:30:30Z |
| format | Article |
| id | doaj.art-429d794cb586443c9c32f96deb592576 |
| institution | Directory Open Access Journal |
| issn | 2296-598X |
| language | English |
| last_indexed | 2024-12-22T17:30:30Z |
| publishDate | 2020-10-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Energy Research |
| spelling | doaj.art-429d794cb586443c9c32f96deb5925762022-12-21T18:18:37ZengFrontiers Media S.A.Frontiers in Energy Research2296-598X2020-10-01810.3389/fenrg.2020.00155546155Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon ElectrodesTim Tichter0Jonathan Schneider1Christina Roth2Angewandte Physikalische Chemie, Freie Universität Berlin, Berlin, GermanyAngewandte Physikalische Chemie, Freie Universität Berlin, Berlin, GermanyLehrstuhl für Werkstoffverfahrenstechnik, Universität Bayreuth, Bayreuth, GermanyThe electrochemical oxidation of VO2+ at planar glassy carbon electrodes is investigated via stationary and rotating linear sweep voltammetry as well as via chronoamperometry. It is demonstrated that introducing finite kinetic rate constants into the Butler-Volmer equation captures the experimentally observed concentration dependence of the ordinate intercept in Koutecký-Levich plots that cannot be explained by using the classical model. This new concept leads to a three-term Koutecký-Levich equation considering mass transport limitations, Butler-Volmer kinetics, as well as finite heterogeneous kinetics simultaneously. Based on these findings it is pointed out that stationary linear sweep voltammetry followed by an irreversible Randles-Ševčík analysis is not sufficient for deducing the electrode kinetics of the VO2+-oxidation. In contrast, it is verified experimentally and theoretically that a Tafel analysis will still provide reasonable values of k0 = 1.35 · 10−5 cm/s and α = 0.38, respectively. Finally, it is shown that introducing the concept of finite heterogeneous kinetics into the theory of stationary linear sweep voltammetry also explains the failure of the irreversible Randles-Ševčík relation leading to an extension of the classical model and providing insight into the electrochemical oxidation reaction of VO2+.https://www.frontiersin.org/article/10.3389/fenrg.2020.00155/fullvanadium redox-flow batteriesrotating disc electrodelinear sweep voltammetryKoutecký-Levich analysisTafel analysis |
| spellingShingle | Tim Tichter Jonathan Schneider Christina Roth Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes Frontiers in Energy Research vanadium redox-flow batteries rotating disc electrode linear sweep voltammetry Koutecký-Levich analysis Tafel analysis |
| title | Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes |
| title_full | Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes |
| title_fullStr | Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes |
| title_full_unstemmed | Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes |
| title_short | Finite Heterogeneous Rate Constants for the Electrochemical Oxidation of VO2+ at Glassy Carbon Electrodes |
| title_sort | finite heterogeneous rate constants for the electrochemical oxidation of vo2 at glassy carbon electrodes |
| topic | vanadium redox-flow batteries rotating disc electrode linear sweep voltammetry Koutecký-Levich analysis Tafel analysis |
| url | https://www.frontiersin.org/article/10.3389/fenrg.2020.00155/full |
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