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Issue 31, 2018
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In situ electrochemical electron paramagnetic resonance spectroscopy as a tool to probe electrical double layer capacitance

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Abstract

Electron paramagnetic resonance (EPR) spectroscopy is applied in situ to monitor the electrochemical capacitance of activated carbon in aqueous solutions, thereby revealing aspects of the charge storage mechanism. The EPR signal of activated carbon increases during the charging process and returns reversibly when discharged. Simulation of the spectral lineshape and its temperature dependence indicate that two kinds of spins exist: spin at defects giving rise to a narrow signal, and spins associated with surface-bound aromatic moieties causing a broad signal. A potential-dependent response of the narrow feature is seen in each of the electrolyte solutions used, while changes of the broad feature occur only at higher electrolyte concentrations. The results suggest that the observed increase of unpaired electron density on activated carbon is due to the formation of radical species due to reduction of functional groups. The potential dependence of the broad feature at higher electrolyte concentrations may be related to the further adsorption of ions into the deep porous structure of activated carbon.

Graphical abstract: In situ electrochemical electron paramagnetic resonance spectroscopy as a tool to probe electrical double layer capacitance

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Publication details

The article was received on 18 Jan 2018, accepted on 07 Mar 2018 and first published on 15 Mar 2018


Article type: Communication
DOI: 10.1039/C8CC00450A
Citation: Chem. Commun., 2018,54, 3827-3830
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    In situ electrochemical electron paramagnetic resonance spectroscopy as a tool to probe electrical double layer capacitance

    B. Wang, A. J. Fielding and R. A. W. Dryfe, Chem. Commun., 2018, 54, 3827
    DOI: 10.1039/C8CC00450A

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