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

MATERIALS TODAY

卷:49

Article

Morton, Justin A.¹  Khavari, Mohammad^1,2  Qin, Ling³  Maciejewska, Barbara M.²  Tyurnina, Anastasia, V⁴  Grobert, Nicole^2,7  Eskin, Dmitry G.⁴  Mi, Jiawei³  Porfyrakis, Kyriakos⁵  Prentice, Paul⁶  Tzanakis, Iakovos^1,2 

[1] Oxford Brookes Univ, Coll Cl, Sch Engn Comp & Math, Oxford OX33 1HX, England

[2] Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England

[3] Univ Hull, Dept Engn, Cottingham Rd, Kingston Upon Hull HU6 7RX, N Humberside, England

[4] Brunel Univ London, Brunel Ctr Adv Solidificat Technol, Kingston Lane, London UB8 3PH, England

[5] Univ Greenwich, Fac Sci & Engn, Cent Ave, Chatham ME4 4TB, Kent, England

[6] Univ Glasgow, Sch Engn, Cavitat Lab, Univ Ave, Glasgow G128QQ, Lanark, Scotland

[7] Williams Adv Engn, Grove OX12 0DQ, Oxfordshire, England

关键词: Ultrasonic exfoliation;    Sono-exfoliation;    Cavitation;    Shock wave;    Liquid-jet;    Acoustic streaming;    Graphene;    Bubble dynamics;   

DOI  :  10.1016/j.mattod.2021.05.005

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

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