Nucleation and Stability of Nanobubbles: from Experiments to Theory

Friday, 17 March – 11:00am – 12:00pm (SAN, School Seminar)

Location: Chemistry Lecture Theatre 4 and Online (Zoom)

Speaker: Dr Hongjie An, Griffith University

Host:  Prof. Chiara Neto

Abstract: Nanobubbles have been controversial since they were first proposed to exist. Their anomalous properties— small contact angles and longevity, robust to destruction or dissolution — defy most classical expectations for how bubbles should behave. Sustained academic scepticism over the very existence of nanobubbles stands in tension with their place at the centre of a multi-billion industry. Although application has long steamed ahead of fundamentals, the yawning gap between the two must be bridged if nanobubbles are to be safely deployed in ambitious frontiers such as medicine. Do nanobubbles exist? How do we prove it unambiguously? How do they survive? This talk summarizes our winding journey in surface nanobubbles, from searching nanobubble existence, overcoming an unexpected contamination issue affecting many early papers (including our own), reserving the three-phase contact line pinning, to the development of a single model capable of explaining most known properties of surface nanobubbles. I will also cover the topic of micro-pancakes and nucleation of nanobubbles by solvent exchange. Finally, I discuss how our experiences with surface nanobubbles help to advance our still shaky understanding of freely standing bulk nanobubbles, also known as ultrafine bubbles. These fundamental studies are crucial for understanding the properties of nanobubbles and their applications.

 Bio: Dr. Hongjie An is currently a Senior Lecturer/ARC Future Fellow in Queensland Micro- and Nanotechnology Centre, Griffith University. He received the PhD degree in Biomedical Engineering at Shanghai Jiao Tong University in 2006. He has been a postdoctoral research fellow in Flinders University, the University of Adelaide, and ANU. After that, he joined in the cavitation lab in Nanyang Technology University as a Senior Research Fellow to study the properties of liquids and bubbles at the nanoscale. He joined in Griffith University as ARC Future Fellowship and study fundamentals and applications of nanobubbles. He has diverse interdisciplinary research experience at the intersection of biology, physics, and the interfacial and material sciences. He has been specialized in developing advanced microscopy techniques towards a variety of research problems in physical and biological sciences. His research interests are diverse: single-molecule imaging and nano-manipulation, cytotoxicity, nanomaterials including nanobubbles/nanodroplets, catalysis at the interface of gas/liquids, 2D materials, nanomedicines, and renewable energy.