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

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

Morton, Justin A., Khavari, Mohammad, Qin, Ling, Maciejewska, Barbara M., Tyurnina, Anastasia V., Grobert, Nicole, Eskin, Dmitry G., Mi, Jiawei, Porfyrakis, Kyriakos ORCID: 0000-0003-1364-0261, Prentice, Paul and Tzanakis, Iakovos (2021) New insights into sono-exfoliation mechanisms of graphite: in situ high-speed imaging studies and acoustic measurements. Materials Today, 49. pp. 10-22. ISSN 1369-7021 (doi:https://doi.org/10.1016/j.mattod.2021.05.005)

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Abstract

The application of ultrasound and acoustic cavitation in liquid exfoliation of bulk layered materials isa 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: Article
Uncontrolled Keywords: Ultrasonic exfoliation; sono-exfoliation; cavitation; shock wave; liquid-jet; acoustic streaming; graphene; bubble dynamics
Subjects: Q Science > QD Chemistry
T Technology > T Technology (General)
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > School of Science (SCI)
Last Modified: 05 Jan 2022 14:25
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
Selected for GREAT 2019: None
Selected for REF2021: None
URI: http://gala.gre.ac.uk/id/eprint/34227

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