金属诱导二维过渡金属硫族化合物相变及界面功能研究

Two-dimensional transition metal dichalcogenides(2D TMD) hold great promise for applications in electronic devices of next generation owing to their unique structures and outstanding properties，and the contact between TMD and metals plays an important role in determining the performance of electronic devices. Recently experimental studies reported phase transitions of TMD on specific metal substrates; however, there is little research on the trend and influencing factors of phase transitions due to the complexity of the system. We plan to combine first principles with Jellium model to develop a method for carrying out structure and energy optimizations of large-scale TMD/metal systems. Energetics and kinetics of phase transitions of TMD on noble and 3d/4d transition metals are investigated, as well as interface functionality. In particular, we explore the dependence of phase transitions in TMD on the metal surface states in terms of the interface coupling. Then we further conceive to tune the trend of phase transitions in TMD on metal substrates by implanting atomic species at the interface, or applying external field or pressure vertical to the interface, and a series of properties such as charge transfer and electron orbit hybridization are obtained. Furthermore, the study is extended from monolayer to multi-layer TMD systems, to explore the layer-dependent phase transition. This project should shed light on fabricating high-performance 2D TMD devices.

二维过渡金属硫族化合物（TMD）因独特的结构和优异的性能有望用于制造下一代电子器件，但其与金属的接触是决定器件性能的关键。近期实验发现TMD在特定金属基底上出现结构相变，但对相变规律和关键影响因素因体系复杂而鲜有研究。申请人拟结合第一性原理与凝胶模型率先发展用于描述大尺度TMD/金属体系结构和能量优化的计算方法，开展3d/4d过渡金属和贵金属等基底上TMD结构相变、相变动力学及界面功能性研究，从界面耦合角度探索TMD结构相变与金属表面态之间的关联。在此基础上，通过界面原子插层、施加外电场和面外压力等方式调控TMD的结构相变，获得界面电荷转移、电子轨道杂化等系列性质，并进一步将研究从单层扩展到多层TMD体系，探究层数依赖的结构相变规律。本项目研究将为构筑高性能二维过渡金属硫族化合物器件提供理论基础。

该项目实施以来，围绕金属诱导二维过渡金属硫族化合物(MX2)相变及界面功能，过渡金属硫族化合物纳米带结构相变及相变动力学，开展了系统性的研究工作。通过第一性原理计算，我们发现MoTe2在Cu(111), Ni(111) 和Ti(0001)金属表面呈现1T’ 相态，而MoSe2仅在Ti(0001)金属表面呈现1T’ 相态，进一步研究表明1T’-MoTe2/Cu(111), 1T’-MoTe2/Ni(111)和1T’-MoTe2/Ti(0001)具有高电催化析氢性能。 第一性原理计算表明MX2纳米带的相稳定性可以转变。随着纳米带尺度的减小，2H相能量变高，1T’-WSe2稳定的最长尺度为2.50nm。本项目的研究为过渡金属硫族化合物科学研究和器件应用提供理论基础。此外，申请人探索了B40团簇组装的过渡金属嵌入的低维功能化B40材料；La掺杂的立方体硼团簇La6&[La@B24]+ 和 La6&[La@B24]构建的一维纳米线La10B32，二维材料La3B10和三维晶体LaB6；一系列双层中尺度硼团簇B54，B60，B62通用结构模式(围绕中心B38双层六棱柱腰部存在1，2，3个B6环)； 依据孤立B4C3分布规则构建的一系列B-C富勒烯。同时，对N掺杂类石墨碳中CoN3活性位的甲酸脱氢进行了探索。