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Viologen-Bromide Dual-Redox Ionic Solid Complexes: Understanding Their Electrochemical Formation and Proton-Accompanied Redox Chemistry

Title
Viologen-Bromide Dual-Redox Ionic Solid Complexes: Understanding Their Electrochemical Formation and Proton-Accompanied Redox Chemistry
Author
장진호
Keywords
redox-enhanced electrochemical capacitor; dual-redox ionic solid complexation; proton-accompanied redox chemistry; particle-impact electrochemistry; galvanic exchange reaction
Issue Date
2019-11
Publisher
AMER CHEMICAL SOC
Citation
ACS APPLIED MATERIALS & INTERFACES, v. 11, no. 46, Page. 43659-43670
Abstract
The inhibition of self-discharge in a redox-enhanced electrochemical capacitor (Redox-EC) is crucial for excellent energy retention. Heptyl viologen dibromide (HVBr2) was chosen as a strong candidate of a dual-redox species in Redox-EC due to its solid complexations during the charging process, at which HV2+ is electrochemically reduced to HV+center dot and form a solid complex, [HV+center dot center dot Br-], on an anode while Br- is electro-oxidized to Br-3(-) and renders [HV2+center dot 2Br(3)(-)] on a cathode. The solid complexes could not transfer across the separator, resulting in significant diminution of the self-discharge. In this Article, we present detailed electrochemical studies of formation of [HV2+center dot 2Br(3)(-)] and [HV+center dot center dot Br-], their redox features, and galvanic exchange reactions between the two types of dual-redox ionic solids on a Pt ultra-microelectrode (UME) in neutral (0.33 M Na2SO4) and acidic (1 M H2SO4) solutions. Most importantly, through voltammetric and particle-impact electrochemical analyses, we found that the redox and galvanic exchange reactions of the two dual-redox ionic solid complexes involve H+ transfer, which is the key process to limit the overall kinetics of the electrochemical reactions. We also rationalize the proton-accompanied galvanic exchange reaction based on computational simulation.
URI
https://pubs.acs.org/doi/10.1021/acsami.9b13985https://repository.hanyang.ac.kr/handle/20.500.11754/155119
ISSN
1944-8244; 1944-8252
DOI
10.1021/acsami.9b13985
Appears in Collections:
COLLEGE OF NATURAL SCIENCES[S](자연과학대학) > CHEMISTRY(화학과) > Articles
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