Hear three experts in the field of Raman Spectroscopy discuss Raman, SERS and TERS for 2D materials.
Yury Gogotsi, PhD
Dr. Yury Gogotsi will present 'The Family of 2D Carbides and Nitrides (MXenes).'
Appreciation of the fact that synthesis of two-dimensional (2D) materials does not necessarily require van der Waals bonded layered precursors led to discovery of many new materials, including MXenes – 2D carbides and nitrides of transition metals, produced by selective etching of strongly bonded layered solids. Ti3C2 was first reported in 2011 and set the stage for synthesis of Ti2C, Ta4C3, and other MXenes from their MAX phase precursors, demonstrating three types of possible structures (M2X, M3X2 and M4X3). M5C4 was later produced, further increasing the structural diversity, and bringing the number of theoretically possible compositions to over 100, including those with in-plane and out-of-plane ordering of the metal atoms. Considering various surface terminations of MXenes, the number of distinct compositions increases by another order of magnitude.
The ability of MXenes to form carbonitrides and solid solutions suggests a potentially infinite number of compositions and opens a new era of computationally driven atomistic design of 2D materials. Naturally, structural and chemical variety of MXenes creates a challenge with their characterization. MXenes have already shown a variety of attractive electronic, optical, chemical, and mechanical properties. They possess electrochemically and chemically tunable plasmonic properties, with interband transitions and plasmon resonance peaks covering the entire ultraviolet, visible, and near-infrared range. Raman spectroscopy analysis may enable precise control of the structure, surface chemistry, defects and strain in MXenes.
Asia Sarycheva, PhD
Dr. Asia Sarycheva will present 'Raman spectroscopy of 2D transition metal carbides and nitrides (MXenes).'
Raman spectroscopy is known as a fast and non-destructive tool to characterize molecular vibrations, also known as molecular fingerprints. It is the most frequently used characterization tool for 2D materials, and it has been used to evaluate not only the composition and defects in the structure, but also to determine the mechanical and thermal properties of 2D materials. Moreover, Raman spectra could be collected even from 2D monolayers and also used to determine the number of layers in flakes or films. This big impact on the field shows that it is an essential tool for studying new families of 2D materials. One of those families is MXenes, 2-dimensional transition metal carbides and nitrides, which were discovered at Drexel University in 2011 and already explored in a large variety of applications: from energy storage to wireless communication devices.
During this talk, you will learn about the first systematic study of Raman spectra of various stoichiometric MXenes and their solid solutions. We have investigated the effects of their physical state, composition, surface chemistry, and flake stacking on the vibrational modes, and used the knowledge for the quality analysis and in-situ experiments, such as Raman electrochemistry and surface enhanced Raman spectroscopy (SERS). This work is the first step towards meaningful in-situ experiments that will allow us to understand electrochemical, mechanical, and many other properties on a micro-scale, ultimately leading to a better understanding of the correlations between MXene structure, processing, properties, and performance.
Andrey Krayev will discuss 'Comprehensive Nanoscale Imaging of MXenes using AFM and TERS.'
In the third presentation of our webinar we’ll demonstrate how the use of combined AFM-Raman system can help with nanoscale imaging of MXenes. Topography, surface potential and capacitance information provided by AFM allows observation of nanoscale defects, such as wrinkles and folds, in few-layer MXene sheets or formation of oxides along the edges of the aging sheets. Tip enhanced Raman spectroscopy (TERS) imaging in its turn enables nanoscale Raman imaging of MXene crystals with spatial resolution comparable with that provided in conventional AFM channels, thus allowing direct cross-correlation of the AFM and Raman results at the nanoscale.
We’ll demonstrate that TERS spectra of wrinkles, which almost inevitably form when the monolayer or few-layer MXene sheets are deposited on the surface from colloidal solution, differ significantly from the TERS spectra of adjacent flat material. We’ll also show the evolution of the TERS spectra as the number of layers in MXene crystals increases.
Finally we’ll demonstrate that TERS imaging is applicable not only for characterization of the individual MXene crystals, but also the vertical heterostructures with 2D semiconductors (MoS2) and graphene oxide.
Join us and learn more about MXenes
Yury Gogotsi is Distinguished University Professor and Charles T. and Ruth M. Bach Professor of Materials Science and Engineering at Drexel University. He also serves as Director of the A.J. Drexel Nanomaterials Institute. His research group works on 2D carbides, nanostructured carbons, and other nanomaterials for energy, water and biomedical applications. He is recognized as Highly Cited Researcher in Materials Science and Chemistry, and Citations Laureate by Thomson-Reuters/Clarivate Analytics. He has received numerous awards for his research and has been elected a Fellow of the World Academy of Ceramics, the European Academy of Sciences, American Association for Advancement of Science, Materials Research Society, American Ceramic Society, the Electrochemical Society, Royal Society of Chemistry, and the International Society of Electrochemistry. He holds honorary doctorates from several Universities in France and Ukraine. He is acting as Associate Editor of ACS Nano.
Asia (A-see-a) Sarycheva is a postdoctoral fellow in the Energy Storage group. Her research interests are in the development of in-situ vibrational spectroscopical methods for the analysis of the interfaces. At Berkeley Lab, her work focuses on investigating of composition and kinetics of the SEI layer in Li-based electrochemical systems. She has graduated with B.Sc. and M.Sc. in Material Science from Moscow State University, where she worked on Surface-Enhanced Raman Spectroscopy (SERS) with professor Eugene Goodilin. After working for a year in the industry, where she worked on the back-etching process for CCD cameras used in an aerospace application, she joined Drexel Nanomaterials Institute as a Ph.D. student, where she worked on a family of 2D materials MXenes. Under the supervision of professor Yury Gogotsi, she developed several MXene-based devices: SERS sensor, radio-frequency antennas RFID tags, and electromagnetic speakers. Her Ph.D. thesis focuses on the understanding of MXenes’ vibrational properties, funded by DOE EFRC, Fluid Interface Reactions, Structures and Transport (FIRST) center. In addition to her Ph.D. studies, she served as a president of the Material Research Society (MRS) student chapter and organized a summer ASM materials camp for high school students
Andrey Krayev received his Master’s degree from the Moscow Institute of Physics and Technology, in 1991. In 2001, he started to use SPM, while working as an application scientist for QPT, Inc. Since 2008, he was the CTO at AIST-NT, Inc. and was actively involved in development of the TERS technique and its implementation for real world applications. Since the acquisition of AIST-NT technology by HORIBA in July of 2017, Andrey has held the position of the US AFM-Raman manager at Horiba. He continues active development of TERS-related applications for advanced characterization of 2D materials and beyond.