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PUBLISHED ONLINE: 20 MARCH 2013|http://www.nature.com/doifinder/10.1038/nchem.1589
Web End =DOI: 10.1038/NCHEM.1589
The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets
Recent research has shown that in addition to the composition and arrangement of atoms in materials, dimensionality plays a crucial role in determining their fundamental properties. This
has been most strikingly highlighted over the past few years with two-dimensional (2D) graphene, which exhibits exotic condensed-matter phenomena that are absent in bulk graphite13. The rapid pace of progress in graphene and the methodology developed in preparing ultrathin layers has led to exploration of other 2D materials417. In particular, single layers of transition metal dichalcogenides (TMDs) with lamellar structures similar to that of graphite have received signicant attention because some of them are semiconductors with sizable bandgaps and are naturally abundant5,6.
Graphene, while being fundamentally and technologically interesting for a variety of applications, is chemically inert and can only be made active by functionalization with desired molecules18, which in turn results in the loss of some of its exotic properties. In contrast, single-layered 2D TMDs whose generalized formula is MX2, where M is a transition metal of groups 410 and X is a chalcogen (Fig. 1) exhibit versatile chemistry. This oers opportunities for fundamental and technological research in a variety of elds including catalysis, energy storage, sensing and electronic devices such as eld-eect transistors and logic circuits.
The properties of bulk TMDs are diverse ranging from insulators such as HfS2, semiconductors such as MoS2 and WS2, semi-metals such as WTe2 and TiSe2, to true metals such as NbS2 and VSe2. A few bulk TMDs such as NbSe2 and TaS2 exhibit low-temperature phenomena including superconductivity, charge density wave (CDW, a periodic distortion of the crystal lattice) and Mott transition (metal to non-metal transition)1921. Exfoliation of these materials into mono- or few-layers largely preserves their properties, and also leads to additional characteristics due to connement eects79. The chemistry of MX2 compounds thus oers opportunities for going beyond graphene and opening up new fundamental and technological pathways for inorganic 2D materials.
Manish Chhowalla1*, Hyeon Suk Shin2, Goki Eda3,4,5, Lain-Jong Li6, Kian Ping Loh4,5 and Hua Zhang7
Ultrathin two-dimensional nanosheets of layered transition metal dichalcogenides (TMDs) are fundamentally and technologically intriguing. In contrast to the graphene sheet, they are chemically versatile....