CAREER: Mechanism-Guided Synthesis of Functional MNenes

About This Grant

NON-TECHNICAL SUMMARY This CAREER project, with support from the Solid State and Materials Chemistry Program and the Ceramics Program, both in the Mathematical and Physical Sciences Directorate, aims to create a new class of two-dimensional (2D) materials derived from earth-abundant transition metals such as titanium, vanadium, chromium, and molybdenum. These materials, known as carbide and nitride MXenes, possess chemical and electronic characteristics similar to noble metals but are much less expensive. The building blocks of these layered materials are hundreds of times thinner than a human hair and more electronically conductive than most metals. This has the potential for enabling transformative advances across biomedicine, energy, food, transportation, and health. The carbide materials are experimentally accessible but degrade rapidly in air and water, restricting their practical use. By contrast, the nitride MXenes (MNenes) are predicted to be substantially more stable, yet only two phases have been prepared so far, leaving many other variations unrealized. This CAREER project employs a new synthesis strategy to create different MNenes for applications ranging from clean energy and high-capacity energy storage to quantum computing and electrochemical manufacturing. By integrating real-time characterization with advanced synthesis and computational tools, the project aims to uncover how the atomic structure of MNenes controls their properties, stability, and performance, guiding the design of next generation 2D materials while accelerating discovery across diverse fields. The project engages K-12 students in hands-on research through the On-the-Fly Lab program, involves undergraduates from Historically Black Colleges and Universities in a summer research program, and provides U.S. graduate students with mentoring, career development, and international collaboration opportunities. It also extends mentoring and outreach to students across geographic and institutional boundaries through the Connect with Dr. Djire (CwD) initiative. Overall, this CAREER project will strengthen U.S. leadership and national security in critical materials while cultivating a highly skilled scientific workforce through broadened participation in STEM and the advancement of transformative materials technologies. TECHNICAL SUMMARY MXenes, 2D nanomaterials derived from the selective etching of the A element from ceramic MAX phases (where M is a transition metal, A is a group 13-16 element, and X is carbon or nitrogen), combine high electronic conductivity, large surface area, and tunable chemistry, making them a versatile platform for addressing existing and emerging energy and catalysis challenges. However, currently available carbide MXenes are constrained by poor chemical and electrochemical stability, which limits their practical applications. In contrast, nitride MXenes (MNenes) are expected to be far more stable but remain largely inaccessible, as traditional synthesis methods such as hydrofluoric acid etching have been unsuccessful due to the strong M-A bonds in the parent MAX phases. This CAREER project, with support from the Solid State and Materials Chemistry Program and the Ceramics Program, aims to develop stable MNenes using innovative molten-salt fluoride chemistries, testing the hypothesis that controlled oxidation of the A layer weakens the M-A bond in the parent MAX phase, resulting in selective A-layer removal. The research addresses three key gaps: limited understanding of the MAX-to-MNene etching mechanism, the scarcity of nitride MAX precursors, and the lack of structure-property-stability relationships urgently needed to elucidate their fundamental behavior and unlock their full potential. Combining advanced molten-salt etching with operando synchrotron X-ray diffraction, quasielastic neutron scattering, and first-principles calculations, this integrated experimental-computational approach will generate predictive design rules for stable and highly functional MNenes, advancing next-generation 2D materials discovery. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.