Electrocatalytic activity of nitrogen-doped CNT graphite felt hybrid for all-vanadium redox flow batteries

Yang, Dae Sik; Lee, Jang Yong; Jo, Sang-Woo; Yoon, Sang Jun; Kim, Tae-Ho; Hong, Young Taik

doi:10.1016/j.ijhydene.2017.11.145

Cited by 45 publications

(38 citation statements)

References 36 publications

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“…The substantially improved performance was attributed to various features of these catalysts: changes of the electronic structure of the CNTs by embedded nitrogen should influence favorably adsorption characteristics for vanadium-species; the doping causes generation of defect sites which are frequently more active catalytically; and the amount of surface oxygen species, which in many studies has been identified as being critically involved in the redox reactions, is increased; the doping makes the CNTs more accessible, i.e., the electrochemically active surface is increased probably because of a more hydrophilic surface. Nitrogen-doped CNTs were prepared using metal phthalocyanines as precursors on graphite felt [260]. Best results in terms of high nitrogen concentration, improved wettability and electronic conductivity were obtained with iron phthalocyanine, yielding an increase of energy efficiency of 20% compared with a VRFB using pristine graphite felt.…”

Section: Structural Modification Of Carbonmentioning

confidence: 99%

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Holze

2018

Batteries

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Flow batteries (also: redox batteries or redox flow batteries RFB) are briefly introduced as systems for conversion and storage of electrical energy into chemical energy and back. Their place in the wide range of systems and processes for energy conversion and storage is outlined. Acceleration of electrochemical charge transfer for vanadium-based redox systems desired for improved performance efficiency of these systems is reviewed in detail; relevant data pertaining to other redox systems are added when possibly meriting attention. An attempt is made to separate effects simply caused by enlarged electrochemically active surface area and true (specific) electrocatalytic activity. Because this requires proper definition of the experimental setup and careful examination of experimental results, electrochemical methods employed in the reviewed studies are described first.

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Section: Structural Modification Of Carbonmentioning

confidence: 99%

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Holze

2018

Batteries

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“…[21,22] Prior treatment to increase the activity is therefore widely considered in the form of hydroxylation or carboxylation, attachment of functional groups, sulfonating, or heteroatom doping. [23][24][25][26][27][28][29] Similar to the treatment of graphitefelt electrodes, these procedures are expected to damage the graphitic basal plane, which consequently introduces edge sites. Therefore, the real activity enhancement of the treatment is hard to separate from the pure addition of active edge sites.…”

Section: Introductionmentioning

confidence: 99%

Influence and Electrochemical Stability of Oxygen Groups and Edge Sites in Vanadium Redox Reactions

et al. 2020

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It is widely accepted that surface-active oxygen functional groups (OFGs) effectively catalyze the vanadium redox reactions. Initial graphitic edge sites, OFGs and their electrochemical stability were examined using graphite felts, which were modified with multi-walled carbon nanotubes and activated with KOH. It is demonstrated that OFGs cannot exclusively be responsible for the electrocatalysis since they did not correlate to the electrochemical activity. The surface composition after electrochemical cycling in the positive half-cell was still different for all samples but did not reflect the performance either. However, a correlation was found between the activity and stable edge site defects. There was neither a correlation between the electrocatalytic activity and the amount of oxygen, nor for the kind of OFG in the negative half-cell. The oxygen concentration after electrochemistry was very similar, even more highlighting the importance of edge sites in the V III /V II redox reaction. The results of this work indicate that the major electrocatalytic effect for both half-cell redox reactions is related to stable graphitic edge sites in sufficient quantity.

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“…Compared with the cell with pristine GF, the cell equipped with hydroxyl MWCNTs/GF shows higher efficiencies at different current densities. e higher energy efficiency of the hydroxyl MWCNTs/GFbased cell is attributed to the enhanced conductivity and increased reactive sites of hydroxyl MWCNTs/GF electrode, resulting in improved overall cell performance [31,32].…”

Section: Samplesmentioning

confidence: 99%

A Comprehensive Study on Hydroxyl Multiwalled Carbon Nanotubes Used as Catalysts for VO₂⁺/VO²⁺ Reaction in Vanadium Redox Flow Battery

Bai

et al. 2019

Journal of Chemistry

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A comprehensive study on the hydroxyl multiwalled carbon nanotubes (hydroxyl MWCNTs) as catalysts in a positive reaction was performed to improve the efficiency of the vanadium redox flow battery (VRFB). e physicochemical properties of the hydroxyl MWCNT-modified electrode were characterized by using a scanning electron microscope (SEM), conductivity measurement, Brunner-Emmet-Teller (BET) measurement, X-ray photoelectron spectroscopy (XPS) analysis, cyclic voltammetry (CV) tests, electrochemical impedance spectroscopy (EIS) analysis, and charge-discharge tests. e prepared composite electrode possesses a huge amount of oxygen-containing groups, high-specific surface area, high electrical conductivity, and high catalytic activity towards the VO 2 + /VO 2+ reaction based on physicochemical characterization. e hydroxyl MWCNT-modified graphite felt (hydroxyl MWCNTs/GF) shows the best cell performance with the energy efficiency of 79.74% and remains in high stability after 50 cycles. e improved cell performance is probably ascribed to the increase in active sites, fast charge transfer, and mass transfer rate of the introduced hydroxyl MWCNTs.

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Electrocatalytic activity of nitrogen-doped CNT graphite felt hybrid for all-vanadium redox flow batteries

Cited by 45 publications

References 36 publications

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Influence and Electrochemical Stability of Oxygen Groups and Edge Sites in Vanadium Redox Reactions

A Comprehensive Study on Hydroxyl Multiwalled Carbon Nanotubes Used as Catalysts for VO₂⁺/VO²⁺ Reaction in Vanadium Redox Flow Battery

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Electrocatalytic activity of nitrogen-doped CNT graphite felt hybrid for all-vanadium redox flow batteries

Cited by 45 publications

References 36 publications

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Influence and Electrochemical Stability of Oxygen Groups and Edge Sites in Vanadium Redox Reactions

A Comprehensive Study on Hydroxyl Multiwalled Carbon Nanotubes Used as Catalysts for VO2+/VO2+ Reaction in Vanadium Redox Flow Battery

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Product

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A Comprehensive Study on Hydroxyl Multiwalled Carbon Nanotubes Used as Catalysts for VO₂⁺/VO²⁺ Reaction in Vanadium Redox Flow Battery