Nemani, Srinivasa KartikZhang, BowenWyatt, Brian C.Hood, Zachary D.Manna, SukritaKhaledialidusti, RasoulHong, WeichenSternberg, Michael G.Sankaranarayanan, Subramanian K. R. S.Anasori, Babak2023-02-232023-02-232021-06Nemani, S. K., Zhang, B., Wyatt, B. C., Hood, Z. D., Manna, S., Khaledialidusti, R., Hong, W., Sternberg, M. G., Sankaranarayanan, S. K. R. S., & Anasori, B. (2021). High-Entropy 2D Carbide MXenes: TiVNbMoC3 and TiVCrMoC3. ACS Nano. https://doi.org/10.1021/acsnano.1c02775https://hdl.handle.net/1805/31425Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are a fast-growing family of 2D materials. MXenes 2D flakes have n + 1 (n = 1–4) atomic layers of transition metals interleaved by carbon/nitrogen layers, but to-date remain limited in composition to one or two transition metals. In this study, by implementing four transition metals, we report the synthesis of multi-principal-element high-entropy M4C3Tx MXenes. Specifically, we introduce two high-entropy MXenes, TiVNbMoC3Tx and TiVCrMoC3Tx, as well as their precursor TiVNbMoAlC3 and TiVCrMoAlC3 high-entropy MAX phases. We used a combination of real and reciprocal space characterization (X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and scanning transmission electron microscopy) to establish the structure, phase purity, and equimolar distribution of the four transition metals in high-entropy MAX and MXene phases. We use first-principles calculations to compute the formation energies and explore synthesizability of these high-entropy MAX phases. We also show that when three transition metals are used instead of four, under similar synthesis conditions to those of the four-transition-metal MAX phase, two different MAX phases can be formed (i.e., no pure single-phase forms). This finding indicates the importance of configurational entropy in stabilizing the desired single-phase high-entropy MAX over multiphases of MAX, which is essential for the synthesis of phase-pure high-entropy MXenes. The synthesis of high-entropy MXenes significantly expands the compositional variety of the MXene family to further tune their properties, including electronic, magnetic, electrochemical, catalytic, high temperature stability, and mechanical behavior.enPublisher PolicyMXenes2D materialsmulti-principal elementsArticle