Phase transition in two dimensional molybdenum disulfide (MoS₂) can be induced by several methods and has been investigated for decades. Alkali metal insertion of MoS₂ had been proved an effective method to cause phase transition early in 1970s, and has been gaining renewed interest recently, due to the possible application of MoS₂ in energy storage. The alkali metal intercalation of MoS₂ has been studied by various techniques, among which in-situ transmission electron microscopy (TEM) provides unique capability of real time resolving the structural evolution of the materials at high spatial resolutions. Here by in-situ TEM technique we investigated the structural evolution of MoS₂ upon lithium and sodium intercalation, along with transformation of the nanosheet and variation of the electron diffraction patterns. The intercalation process is accompanied by emergence of superstructures, which exist in several forms. The ion intercalation results in phase transition of MoS₂ from 2H to 1T, and the driving mechanism of the phase transition are discussed. The work provides a more comprehensive understanding of ion intercalation induced phase transition of MoS₂.

二维二硫化钼（MoS ₂）的相变可以通过几种方法诱导，并且已经进行了数十年的研究。1970年代初，碱金属插入MoS ₂已被证明是引起相变的有效方法，并且由于MoS ₂可能在储能中的应用，近来引起了新的兴趣。MoS ₂的碱金属插层已通过各种技术进行了研究，其中原位透射电子显微镜（TEM）提供了实时解决高空间分辨率材料结构演变的独特功能。在这里，通过原位TEM技术，我们研究了MoS的结构演变₂在锂和嵌入钠，与纳米片的改造和变化的电子衍射图案的沿。插层过程伴随着上层结构的出现，上层结构以几种形式存在。离子嵌入导致MoS ₂从2H到1T的相变，并讨论了相变的驱动机理。这项工作为MoS ₂的离子嵌入诱导的相变提供了更全面的理解。