The research group of Huang Fuqiang, researcher of Shanghai Institute of silicate, Chinese Academy of Sciences and his collaborators have made important progress in the structural analysis and nonlinear optical properties of 1t '' MoS2

Molybdenum disulfide, as a typical representative of layered transition metal sulfide, has a very rich crystal structure, including 2h, 3R, 1t, 1t 'and 1t' ' Among these different phases, the preparation of 2hmos2 is relatively simple, and many research results have been achieved in the fields of electrocatalysis, photoelectric detection, energy storage, superconductivity and so on However, in recent years, theorists have predicted that metastable phases 1t 'and 1t' '' MoS 2 have very peculiar physical properties, such as quantum spin Hall effect and two-dimensional ferroelectricity This kind of metastable phase molybdenum disulfide has become a research hotspot due to its unique physical properties However, the crystal structure of this metastable phase molybdenum disulfide is in a state of thermodynamic instability, and it will change to 2H MoS 2 at high temperature, so the physical and chemical properties of this kind of material have not been studied Therefore, the preparation and structure analysis of metastable molybdenum disulfide are of great scientific significance Recently, Huang Fuqiang, researcher group of Shanghai Silicate Research Institute, Chinese Academy of Sciences (research group of photoelectric conversion materials and devices), cooperated with researchers from Peking University, Shanghai Jiaotong University and Huazhong University of science and technology to prepare 1t '' MoS 2 crystal by Topological Chemistry Method and analyze its crystal structure for the first time In view of the asymmetric center structure of 1t '' 'MoS 2, the team further studied its nonlinear optical effect, and used different wavelengths of laser to test the second harmonic response of the single-chip 1t' '' MoS 2 crystal, and found that it has the strongest response intensity under the excitation light with the wavelength of 850nm On this basis, the team tested the second harmonic response of polarization, and the measured image was hexagonal petal, corresponding to the third symmetry axis in the intrinsic crystal structure The research results were published in the international famous journal J am Chem SOC (DOI: 10.1021 / JACS 8b12133) under the title of "structural determination and nonlinear optical properties of new 1t '' '- typemos 2 compound" The first co authors of the paper are Fang Yuqiang, a doctoral student at Shanghai Silicate Institute, Hu Xiaozong, a doctoral student at Huazhong University of science and technology, and Hu Xiaozong, a doctoral student at Huazhong University of science and technology Zhao Wei, assistant researcher of Shanghai Silicate Institute, and the co authors are Huang Fuqiang, researcher of Shanghai Silicate Institute, Chinese Academy of Sciences, Zhai Tianyou, Professor of Huazhong University of science and technology, and Liu Pan, Professor of Shanghai Jiaotong University The research results provide a new idea for the study of metastable two-dimensional material system The above research work was supported by national key R & D plan, National Natural Science Foundation, Chinese Academy of Sciences and Shanghai Science and Technology Commission.