Bromate anion reduction: novel autocatalytic (EC″) mechanism of electrochemical processes. Its implication for redox flow batteries of high energy and power densities

Content Provider	Scilit
Author	Vorotyntsev, Mikhail A. Antipov, Anatoly E. Konev, Dmıtry V.
Copyright Year	2017
Abstract	Recent theoretical studies of the bromate electroreduction from strongly acidic solution have been overviewed in view of very high redox-charge and energy densities of this process making it attractive for electric energy sources. Keeping in mind non-electroactivity of the bromate ion the possibility to ensure its rapid transformation via a redox-mediator cycle (EC′ mechanism) is analyzed. Alternative route via the bromine/bromide redox couple and the comproportionation reaction inside the solution phase is considered within the framework of several theoretical approaches based on the conventional Nernst layer model, or on its recently proposed advanced version (Generalized Nernst layer model), on the convective diffusion transport equations. This analysis has revealed that this process corresponds to a novel (EC″) electrochemical mechanism since the transformation of the principal oxidant (bromate) is carried out via autocatalytic redox cycle where the bromate consumption leads to progressive accumulation of the bromine/bromide redox couple catalyzing the process. As a result, even a tracer amount of its component, bromine, in the bulk solution leads under certain conditions to extremely high current densities which may even overcome the diffusion-limited one for bromate, i.e. be well over 1 A/cm2 for concentrated bromate solutions. This analysis allows one to expect that the hydrogen–bromate flow battery may generate very high values of both the current density and specific electric power, over 1 A/cm2 and 1 W/cm2.
Related Links	http://www.degruyter.com/downloadpdf/j/pac.2017.89.issue-10/pac-2017-0306/pac-2017-0306.xml
Ending Page	1448
Page Count	20
Starting Page	1429
ISSN	00334545
e-ISSN	13653075
DOI	10.1515/pac-2017-0306
Journal	Pure and Applied Chemistry
Issue Number	10
Volume Number	89
Language	English
Publisher	Walter de Gruyter GmbH
Publisher Date	2017-08-12
Access Restriction	Open
Subject Keyword	Pure and Applied Chemistry Electrochemistry Autocatalytic Cycle Bromine/bromide Redox Mediation Comproportionation Reaction Convective Transfer Ec′ Mechanism Generalized Nernst Layer Model Individual Diffusion-layer Thicknesses Mendeleev Xx Stagnant Nernst Layer Model Journal: Pure and Applied Chemistry, Vol- 89
Content Type	Text
Resource Type	Article
Subject	Chemistry Chemical Engineering