Among the redox active molecules, methyl viologen (MV) is the most promising redox species in an aqueous organic redox flow battery, featuring the stable redox reaction MV2+/MV•+. Its electrochemical properties and solubility significantly depend on the counter-anion. Herein, we introduce the nitrate as a counter-anion to methyl viologen dication to obtain a new water-soluble methyl viologen compound (MVdN) and identify the effects of nitrate as counter-anion on electrochemical properties of methyl viologen. Nitrate leads to ∼ 3.5 M solubility in water and good electrochemical reversibility (ip,a/ip,c = 0.79, ΔE = 54 mV) with fast mass transfer (D = 5.13 × 10-5 cm2•s-1) of methyl viologen, which is superior to commonly used methyl viologen dichloride(MVdCl). Additionally, flow cell performance from 40 to 100 mA cm-2 exhibited 99% coulombic efficiency and comparable performance with MVdCl. Nitrate could be a promising choice as a counter anion to methyl viologen as aqueous redox active molecule.
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© 2021 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry