Title: The Interlayer Space in Multilayered MXenes and How To Control It
Abstract: The 2D early transition metal carbides known as MXenes – obtained by etching the A-layers from the MAX phases – discovered in 2011 – have generated substantial interest in the scientific community because of their potential in an ever-expanding host of applications. In many of these applications, what is occurring in the interlayer space of multilayers is critical, whether because it leads to delamination, or their dispersion in various solvents or the amount of charge that can be stored among others. Unlike hydrophobic graphene, MXenes are hydrophilic and behave as 2D metals or “conductive clays” a hitherto unknown combination. In this talk I will focus on the “conductive clay” aspects of MXenes. There is a large body of work on clays that was carried out decades ago. Over the years we have exploited this work to understand what is happening in multilayered MXenes Using primarily XRD diffraction, the relationship between etchant used and the swelling of the interlayer space in Ti3C2Tx multilayers will be elucidated. Further how to disperse and stabilize Ti3C2Tx in polar and non-polar solvents is discussed. In short, the relationship between intercalated cations, solvent and interlayer space and the similarities and differences between MXenes and clays will be discussed. Lastly, if time permits, I will briefly touch upon our latest major breakthrough: Massively scalable, water stable, truly 1D TiO2 nanofilaments, with a 5×7 Å2 cross section.
Bio: Prof. Michel W. Barsoum is Distinguished Professor in the Department of Materials Science and Engineering at Drexel University. He is an internationally recognized leader in the area of MAX phases and more recently the 2D solids labeled MXenes derived from the MAX phases. Most recently he also discovered a new universal mechanism – ripplocation – in the deformation of layered solids. With over 500 refereed publications and a Google h index is 140, his work has been cited more than 110,000 times to date. He was on the Web of Science’s highly cited researchers list in 2018 to 2023. In 2020, according to a recent Stanford University study, he had the highest c-index (combines citations and h-index) in the Materials Science subfield in 2022 and was 8th on the all-time list of material scientists in the world. He is a foreign member of the Royal Swedish Society of Engineering Sciences, National Academy of Inventors, fellow of the American Ceramic Soc. and the World Academy of Ceramics. He is the author the books, MAX Phases: Properties of Machinable Carbides and Nitrides and Fundamentals of Ceramics, a leading textbook in his field. In 2020, he was awarded the International Ceramics Prize for basic science by the World Academy of Ceramics. This prize is awarded quadrennially and is one of the highest in his field. The prize was awarded for “… outstanding contribution in opening new horizons in material research and specifically for your pioneering work in MAX phases and their derivatives.”