New insights into sono-exfoliation mechanisms of graphite: in situ high-speed imaging studies and acoustic measurements

Morton, J. A. et al. (2021) New insights into sono-exfoliation mechanisms of graphite: in situ high-speed imaging studies and acoustic measurements. Materials Today, 49, pp. 10-22. (doi: 10.1016/j.mattod.2021.05.005)

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The application of ultrasound and acoustic cavitation in liquid exfoliation of bulk layered materials is a widely used method. However, despite extensive research, the fundamental mechanisms remain far from being fully understood. A number of theories have been proposed to interpret the interactions between cavitation and bulk layered materials and hence to explain the mechanisms of ultrasound assisted exfoliation. Unfortunately, most of the research reported to date is ambiguous or inconclusive due to lack of direct real-time experimental evidence. In this paper, we report systematic work characterising cavitation emissions and observing the exfoliation of graphite in situ, in deionised water under the dynamic interaction with laser and ultrasound induced cavitation bubbles. Using ultra-high-speed optical imaging, we were able to determine the dynamic sequence of graphite exfoliation events on a time scale never reported before. Real-time observations also revealed that shock waves with a pressure magnitude up to 5 MPa and liquid-jets in the range of 80 ms−1, from transient cavitation bubble implosions, were essential for the initiation and propagation of the exfoliation process. On the other hand, bubble oscillations associated with stable cavitation were beneficial for promoting a gentler delamination of graphite layers.

Item Type:Articles
Additional Information:This work has been funded by the UK Engineering and Physical Sciences Research Council (EPSRC), to the project “Sustainable and industrially scalable ultrasonic liquid phase exfoliation technologies for manufacturing 2D advanced functional materials” (EcoUltra2D), with the grant nos. EP/R031665/1; EP/R031401/1; EP/R031819/1; EP/R031975/1. NG also thanks the Royal Society for financial support.
Glasgow Author(s) Enlighten ID:Prentice, Dr Paul
Creator Roles:
Prentice, P.Resources, Writing – review and editing
Authors: Morton, J. A., Khavari, M., Qin, L., Maciejewska, B. M., Tyurnina, A. V., Grobert, N., Eskin, D. G., Mi, J., Porfyrakis, K., Prentice, P., and Tzanakis, I.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Materials Today
ISSN (Online):1873-4103
Published Online:24 June 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Materials Today 49: 10-22
Publisher Policy:Reproduced under a Creative Commons License

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