Metastable MoS 2 : Crystal Structure, Electronic Band Structure, Synthetic Approach and Intriguing Physical Properties

The 2H molybdenum disulfide (MoS 2 ), as a stable hexagonal phase, has been one of the most studied transition metal dichalcogenides over the past decades. In the last five years, the metastable phases of MoS 2 (1T, 1T′, 1T′′, and 1T′′′) have seen a revival of interests. Different from the edge‐sharing [MoS 6 ] trigonal prisms in the 2H MoS 2 phase, these metastable phases are composed of the edge‐sharing [MoS 6 ] octahedra, in which the neighboring Mo−Mo distances differ. Due to the various crystal structures and different electronic configurations of the building [MoS 6 ] motifs, these metastable polytypes are endowed with intriguing physical properties and potential applications in diverse fields. In this Review, the recent research progress on metastable MoS 2 is summarized, especially with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties. The phase structures and electronic band structures are also outlined. In the end, a perspective of the future investigation on metastable MoS 2 is discussed.