Substituent Pattern Effects on the Redox Potentials of Quinone‐Based Active Materials for Aqueous Redox Flow Batteries

Schwan, Sebastian; Schröder, Daniel; Wegner, Hermann A.; Janek, Jürgen; Mollenhauer, Doreen

doi:10.1002/cssc.202000454

Cited by 43 publications

(53 citation statements)

References 31 publications

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“…As more electron density is withdrawn from the oxygens in the Q 2anion, the reduced form is more delocalised and stabilised against re-oxidation. The increase in reduction potential varies slightly for different positions of substitutions for F, as seen previously in the case of other substituents [20][21][22]. When EDGs are substituted instead, the opposite effect is seen (FigureS3).…”

supporting

confidence: 74%

“…The increase in reduction potential varies slightly for different positions of substitutions for F, as seen previously in the case of other substituents. [20][21][22] When EDGs are substituted instead, the opposite effect is seen (Figure S3). Overall, increasing the number of F substitutions leads to approximately linear increase in the reduction potentials of AQ.…”

Section: Effect Of Tuning Quinone Electron Density On Electrochemical...mentioning

confidence: 97%

“…We now explore how varying the electron density of quinones impacts electrochemical CO 2 capture through a F-substituted AQ series. F is a good candidate to be used for fine-tuning because (i) F substituents tend to show a strong negative inductive effect of an EWG that predominates the positive resonance effect of an EDG, 22 (ii) there are various ways to fluorinate AQ selectively [33][34][35] and (iii) the small size of F minimises steric effects, whereas the large substituents can decrease the CO 2 capturing ability, as previously observed in Cl-substituted quinones. 27 The thermodynamics governing the EE and CC steps for AQ derivatives with increasing number of Fsubstituents are now quantified from DFT calculations.…”

Section: Effect Of Tuning Quinone Electron Density On Electrochemical...mentioning

confidence: 99%

“…Both of these challenges can be tackled computationally through quantum chemical calculations. As quinones and their derivatives are also of interest in energy storage applications, several studies have computationally examined their redox properties, including the effect of electron-donating groups (EDGs) and electronwithdrawing groups (EWGs), 20,21 substituent pattern effects 22 and their structure-property relationships. 23 Most of these works are based on density functional theory (DFT), which has proven to be an affordable and reliable way to study redox properties of organic molecules.…”

Section: Introductionmentioning

confidence: 99%

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Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Bui

Hartley

Thom

et al. 2022

Preprint

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Electrochemical carbon dioxide capture has recently emerged as a promising alternative approach to conven- tional energy-intensive carbon capture methods. The most common electrochemical capture approach is to employ redox-active molecules such as quinones. Upon electrochemical reduction, quinones become activated for the chemical capture of CO2. The main disadvantage of this method is the possibility of side-reactions with oxygen, which is present in almost all gas mixtures of interest for carbon capture. This issue can potentially be mitigated by fine-tuning redox potentials through the introduction of electron-withdrawing groups on the quinone ring. In this article, we investigate the thermodynamics of the electron transfer and chemical steps of CO2 capture in different anthraquinone derivatives with a range of substituents. By combining density functional theory calculations and cyclic voltammetry experiments, we discover a trade-off between redox potentials and the strength of CO2 capture. We show that redox potentials can readily be tuned to more positive values to impart stability to oxygen, but as a consequence, significant decreases in CO2 binding free energies are observed. This trade-off must be taken into consideration for the design of improved redox active molecules for electrochemical CO2 capture.

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supporting

confidence: 74%

Section: Effect Of Tuning Quinone Electron Density On Electrochemical...mentioning

confidence: 97%

Section: Effect Of Tuning Quinone Electron Density On Electrochemical...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Bui

Hartley

Thom

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

Section: Effect Of Tuning Quinone Electron Density On Electrochemical...mentioning

confidence: 99%

Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Bui

Hartley

Thom

et al. 2022

Preprint

View full text Add to dashboard Cite

Electrochemical carbon dioxide capture has recently emerged as a promising alternative approach to conventional energy-intensive carbon capture methods. The most common electrochemical capture approach is to employ redox-active molecules such as quinones. Upon electrochemical reduction, quinones become activated for the chemical capture of CO2. The main disadvantage of this method is the possibility of side-reactions with oxygen, which is present in almost all gas mixtures of interest for carbon capture. This issue can potentially be mitigated by fine-tuning redox potentials through the introduction of electron-withdrawing groups on the quinone ring. In this article, we investigate the thermodynamics of the electron transfer and chemical steps of CO2 capture in different anthraquinone derivatives with a range of substituents. By combining density functional theory calculations and cyclic voltammetry experiments, we discover a trade-off between redox potentials and the strength of CO2 capture. We show that redox potentials can readily be tuned to more positive values to impart stability to oxygen, but as a consequence, significant decreases in CO2 binding free energies are observed. This trade-off must be taken into consideration for the design of improved redox active molecules for electrochemical CO2 capture.

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Behaviour of 3,4‐Dihydroxy‐9,10‐Anthraquinone‐2‐Sulfonic Acid in Alkaline Medium: Towards a Long‐Cycling Aqueous Organic Redox Flow Battery

Guihéneuf

Lê

Godet-Bar³

et al. 2021

ChemElectroChem

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The performance of a redox compound in redox flow batteries (RFB) highly depends on the electrolytic medium and operating conditions. It is exemplified in this work with the commercially available and relatively low-cost dye 3,4-dihydroxy-9,10-anthraquinone-2-sulfonic acid (ARS), which was used as negolyte in basic medium. At high pH, the ARS behavior revealed interesting features for RFB applications, such as a low halfwave potential of À 0.99 V (vs Ag/AgCl), negatively shifted by phenolate groups, and an improved solubility compared with acidic medium depending on the nature of the cations. For the highly soluble ARS potassium salt (ARSK), a maximum power density of 117 mW cm À 2 and a demonstrated energy density of 20 Wh L À 1 were obtained with K 4 [Fe(CN) 6 ] as posolyte. The capacity slightly decreased during cycling, reaching 90 % after 325 cycles. A long cycling of ARS sodium salt (ARSNa) over 11 operating months was demonstrated in this work. A slow chemical degradation was highlighted giving rise to the formation of 3-hydroxy-9,10-anthraquinone-2-sulfonic acid (HAQS) as the main degradation product due to hydrodeoxygenation reaction. Interestingly, this compound exhibited high performance in RFB and a good stability with a loss of capacity of 0.29 % per day.

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Substituent Pattern Effects on the Redox Potentials of Quinone‐Based Active Materials for Aqueous Redox Flow Batteries

Cited by 43 publications

References 31 publications

Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

Behaviour of 3,4‐Dihydroxy‐9,10‐Anthraquinone‐2‐Sulfonic Acid in Alkaline Medium: Towards a Long‐Cycling Aqueous Organic Redox Flow Battery

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