Synthesis of Mo 4 VAlC 4 MAX Phase and Two-Dimensional Mo 4 VC 4 MXene with Five Atomic Layers of Transition Metals

作者：Grayson Deysher, Christopher E. Shuck, Kanit Hantanasirisakul, Nathan C. Frey, Alexandre C. Foucher, Kathleen Maleski, Asia Sarycheva, Vivek B. Shenoy, Eric A. Stach, Babak Anasori, Yury Gogotsi · 发表于：ACS Nano · 年份：2019 · DOI：10.1021/acsnano.9b07708 · 被引用次数：721 · 研究领域：MXene and MAX Phase Materials、2D Materials and Applications、Advanced Memory and Neural Computing

MXenes are a family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides with a general formula of M n +1 X n T x, in which two, three, or four atomic layers of a transition metal (M: Ti, Nb, V, Cr, Mo, Ta, etc.) are interleaved with layers of C and/or N (shown as X), and T x represents surface termination groups such as −OH, ═O, and −F. Here, we report the scalable synthesis and characterization of a MXene with five atomic layers of transition metals (Mo 4 VC 4 T x ), by synthesizing its Mo 4 VAlC 4 MAX phase precursor that contains no other MAX phase impurities. These phases display twinning at their central M layers which is not present in any other known MAX phases or MXenes. Transmission electron microscopy and X-ray diffraction were used to examine the structure of both phases. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and high-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy were used to study the composition of these materials. Density functional theory calculations indicate that other five transition metal-layer MAX phases (M′ 4 M″AlC 4 ) may be possible, where M′ and M″ are two different transition metals. The predicted existence of additional Al-containing MAX phases suggests that more M 5 C 4 T x MXenes can be synthesized. Additionally, we characterized the optical, electronic, and thermal properties of Mo 4 VC 4 T x . This study demonstrates t...