MAX Phases and MXenes Synthesis

Over 30 stoichiometric MXenes have already been synthesized, with countless additional solid-solution MXenes. Each MXene has unique optical, electronic, physical, and chemical properties, leading to them being used in nearly every field, from biomedicine to electrochemical energy storage. Our work focuses on the synthesis of different MAX phases and MXenes, including new compositions and structures, spanning all M, A, and X chemistries, and through using all known MXene synthesis approaches. Following are some of the particular directions that we are pursuing:

1. Using multiple M-chemistries

To produce MXenes with tunable properties (M’yM”1-y)n+1XnTx, to stabilize structures that have never existed before (M5X4Tx), and generally determine the effect of chemistry on MXene properties.

2. Synthesis of MXenes from non-aluminum MAX phases

MXenes are a class of 2D materials synthesized by chemical etching of the A element in MAX phases. Since their discovery over 10 years ago, the number of distinct MXenes has grown substantially to include numerous MnXn-1 (n = 1,2,3,4, or 5), their solid solutions (ordered and disordered), and vacancy solids. Most MXenes are produced from aluminum MAX phases, though there have been a few reports of MXenes produced from other A elements (e.g., Si and Ga). We seek to expand the library of accessible MXenes by developing etching protocols (e.g., mixed acid, molten salt, etc.) for other non-aluminum MAX phases facilitating the study of new MXenes and their properties.

3. Etching kinetics

We are trying to understand the kinetics of etching, how the etching chemistry affects MXene properties, and how we can use this knowledge to optimize synthesis of MXenes. 

4. New approaches in delamination of MXenes

We are looking at scalable processes that allow for the possibility of MXenes’ delamination. 

Leading group members: Christopher Shuck, Robert Lord, Mikhail Shekhirev, Alex Inman, Adam Goad, Mark Anayee, Stepan Vorotilo, Teng Zhang

Reference: VahidMohammadi, Armin, Johanna Rosen, and Yury Gogotsi. “The world of two-dimensional carbides and nitrides (MXenes).” Science 372.6547 (2021): eabf1581.