Pseudocapacitive charge storage in Ti3C2Tx MXenes in acid electrolytes is typically described as involving proton intercalation/deintercalation accompanied by redox switching of the Ti centres and protonation/deprotonation of oxygen functional groups. Here we conduct nanoscale electrochemical measurements in a unique experimental configuration, restricting the electrochemical contact area to a small subregion (0.3 µm2) of a monolayer Ti3C2Tx flake. In this unique configuration, proton intercalation into interlayer spaces is not possible, and surface processes are isolated from the bulk processes, characteristic of macroscale electrodes. Analysis of the pseudocapacitive response of differently sized MXene flakes indicates that entire MXene flakes are charged through electrochemical contact of only a small basal plane subregion, corresponding to as little as 3% of the flake surface area. Our observation of pseudocapacitive charging outside the electrochemical contact area is suggestive of a fast transport of protons mechanism across the MXene surface.

Isolation of pseudocapacitive surface processes at monolayer MXene flakes reveals delocalized charging mechanism / M. Brunet Cabré, D. Spurling, P. Martinuz, M. Longhi, C. Schröder, H. Nolan, V. Nicolosi, P.E. Colavita, K. Mckelvey. - In: NATURE COMMUNICATIONS. - ISSN 2041-1723. - 14:1(2023 Jan), pp. 374.1-374.7. [10.1038/s41467-023-35950-1]

Isolation of pseudocapacitive surface processes at monolayer MXene flakes reveals delocalized charging mechanism

M. Longhi;
2023

Abstract

Pseudocapacitive charge storage in Ti3C2Tx MXenes in acid electrolytes is typically described as involving proton intercalation/deintercalation accompanied by redox switching of the Ti centres and protonation/deprotonation of oxygen functional groups. Here we conduct nanoscale electrochemical measurements in a unique experimental configuration, restricting the electrochemical contact area to a small subregion (0.3 µm2) of a monolayer Ti3C2Tx flake. In this unique configuration, proton intercalation into interlayer spaces is not possible, and surface processes are isolated from the bulk processes, characteristic of macroscale electrodes. Analysis of the pseudocapacitive response of differently sized MXene flakes indicates that entire MXene flakes are charged through electrochemical contact of only a small basal plane subregion, corresponding to as little as 3% of the flake surface area. Our observation of pseudocapacitive charging outside the electrochemical contact area is suggestive of a fast transport of protons mechanism across the MXene surface.
Settore CHIM/02 - Chimica Fisica
gen-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/952424
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