The Fastest Growing Family of 2D Materials: Carbides and Nitrides of Transition Metals (MXenes)
Department of Materials Science and Engineering, and A. J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, PA 19104, USA
Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education),Jilin University, Changchun City, 130012, P. R. China
Two-dimensional (2D) solids– the thinnest materials available to us – offer unique properties and a potential path to device miniaturization. The most famous example is graphene, which is an atomically thin layer of carbon atoms bonded together in-plane with sp2 bonds. In 2011, a new family of 2Dsolids –transition metal carbides and nitrides(Ti2C, Ti3C2, Nb4C3, Ti4N3, etc.) – was discovered by Drexel University scientists . These 2D solids with a composition Mn+1Xn (M is a transition metal, X is C or N) werelabeled “MXenes”. More than 20 different carbides, nitrides and carbonitrides have been reportedto date [2-5].A new sub-family of multi-element ordered MXenes was discovered recently . Structure and properties of numerousMXenes have been predicted by the density functional theory, showing that MXenescan be metallic or semiconducting, depending on theircomposition and surface termination.Their elastic constants along the basal plane are expected to be higher than that of the binary carbides. Oxygen or OH terminated MXenes are hydrophilic, but electrically conductive. Hydrazine, urea and other polar organic moleculescan intercalate MXenes leading to an increase of theirc lattice parameter . One of the many potential applications for 2D Ti3C2 is in electrical energy storage devices such as batteries, Li-ion capacitors and supercapacitors [3-5]. Metallic MXenes have a potential for use in electromagnetic interference (EMI) shielding, transparent conducting coatings and many other applications.The reported EMI shielding efficiency values of flexible Ti3C2Txfilms are the highest of any known synthetic materials with similar thickness . Moreover, excellent shielding ability is maintained after adding sodium alginateto create polymer composite films. The 2D structure,combined with high conductivity and good electronic coupling between the layers,is responsible fortheextremely high EMI shielding efficiency of MXenes .
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3. O. Mashtalir, et al, Nature Communication, 4, 1716 (2013)
4. M M. Ghidiu, Nature, 516, 78–81 (2014)
5. B. Anasori, M. R. Lukatskaya, Y. Gogotsi, Nature Reviews Materials,2, 16098 (2017)
6. F. Shahzad, et al, Science353, 1137-1140 (2016)
He has received numerous awards for his research including the European Carbon Association Award, S. Somiya Award from the International Union of Materials Research Societies, International Nanotechnology Prize (Rusnano Prize), R&D 100 Award from R&D Magazine (twice) and two Nano 50 Awards from NASA Nanotech Briefs. He has been elected a Fellow of the American Association for Advancement of Science (AAAS), Materials Research Society, American Ceramic Society, the Electrochemical Society, Royal Society of Chemistry, NANOSMAT Society, as well as Academician of the World Academy of Ceramics and Full Member of the International Institute for the Science of Sintering. He also serves on the MRS Board of Directors.