Issue 26, 2023

Redox-site accessibility of composites containing a 2D redox-active covalent organic framework: from optimization to application

Abstract

Redox-active covalent organic frameworks (RACOFs) can be employed in various functional materials and enesrgy applications. A crucial performance or efficiency indicator is the percentage of redox centres that can be utilised. Herein, the term redox-site accessibility (RSA) is defined and shown to be an effective metric for developing and optimising a 2D RACOF (viz., TpOMe-DAQ made from 2,4,6-trimethoxy-1,3,5-benzenetricarbaldehyde [TpOMe] and 2,6-diaminoanthraquinone [DAQ]) as an anode material for potential organic-battery applications. Pristine TpOMe-DAQ utilises only 0.76% of its redox sites, necessitating the use of conductivity-enhancement strategies such as blending it with different conductive carbons, or performing in situ polymerisation with EDOT (3,4-ethylenedioxythiophene) to form a conductive polymer. While conductive carbon-RACOF composites showed a modest RSA improvement of 4.0%, conductive polymer-RACOF composites boosted the redox-site usage (RSA) to 90% at low mass loadings. The material and electrochemical characteristics of the conductive polymer-RACOF composite containing more-than-necessary conductive polymer showed a reduced surface area but almost identical electrochemical behaviour, compared to the optimal ratio. The high RSA of the optimally loaded composite was replicated in a RACOF-air battery with over 90% active redox sites. We believe that the reported approach and methods, which can be employed on a milligram scale, could serve as a general guide for the electrification and characterisation of RACOFs, as well as for other redox-active porous polymers.

Graphical abstract: Redox-site accessibility of composites containing a 2D redox-active covalent organic framework: from optimization to application

Supplementary files

Article information

Article type
Paper
Submitted
24 Jan 2023
Accepted
13 Apr 2023
First published
13 Apr 2023
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2023,11, 13923-13931

Redox-site accessibility of composites containing a 2D redox-active covalent organic framework: from optimization to application

T. Günther, K. Oka, S. Olsson, M. Åhlén, N. Tohnai and R. Emanuelsson, J. Mater. Chem. A, 2023, 11, 13923 DOI: 10.1039/D3TA00422H

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