Title: Synthesis and Kinetics of Intermetallics and New MAX/MXene

Abstract: Within solid-state chemistry, understanding how a reaction occurs and what affects the reaction pathway gives insight into controlling reactions to produce materials with specific phases, microstructures, or properties. This is especially the case with rapid approaches, such as combustion synthesis, where the reaction is driven by the inherent exothermicity in the system, rather than a predefined heating pattern. To demonstrate this, I will first focus on the Ni/Al reactive system as a model for combustion synthesis kinetics, in addition to switching reaction pathways.

Following this, I will discuss a novel class of materials, MXenes. MXenes are potentially the largest class of 2D materials discovered so far. With a general formula of Mn+1XnTx, M is an early transition metal (Ti, V, Nb, Ta, etc.), X is C and/or N, Tx represents the surface groups (-O, -OH, -F, -Cl), and n = 1–4, over 30 stoichiometric phases have already been discovered, with many more predicted computationally. This class of materials has been widely studied owing to their exceptional properties, including hydrophilicity, scalability, mechanical strength, thermal stability, redox capability, and ease of processing. Because MXenes inherit their structure from Mn+1AXn¬ (MAX) phase precursors, understanding MAX phase synthesis leads to control over flake size, defect density, and chemical composition of the resultant MXene. One understudied, yet important class of MXenes are solid-solution MXenes, where multiple elements are randomly distributed within the M layers. Herein, a set of multi-M chemistries (Mo, V, Ti, Nb) are used to study the effect of structure and chemistry on MXenes. While solid-solution MXenes have unique and tunable chemical, optical, and electronic properties, they also enable the formation of novel MXenes that cannot exist otherwise. By choosing specific chemistries, we can then begin to understand fundamental aspects of MXene chemistry and structure.

Bio: Dr. Christopher E. Shuck received his Ph.D. in 2018 from the University of Notre Dame in Chemical and Biomolecular Engineering, and B.S.E. in 2013 from Princeton University in Chemical and Biological Engineering. He received numerous awards for his work, including the Fulbright Scholarship in 2016. He is currently working as a research assistant professor at the A.J. Drexel Nanomaterials Institute, Drexel University. His research interests include chemical kinetics, materials synthesis, and 2D materials. Christopher’s work has led to a direct change in the definition of both MAX phases and MXenes (Discovery of M₅AX₄ and M₅X₄T_x MXene), he has pioneered work into solid-solution MXenes, and has applied MXene work into many fields, including electrochemical energy storage, electromagnetic interference shielding, and biomedicine.