表面化学法调控二维过渡金属硫属化合物超薄纳米结构的本征磁性质

With the advantages of variety options of elements and optimizing structures than that of graphene, ultrathin two-dimensional (2D) transition metal dichalcogenide (TMDC) with intrinsic magnetism is emerging as crucial materials for the design of new-generation spintronic devices. Considering the extremely high specific surface area of 2D nanosheet enabling their surface phase to be as important as bulk counterparts, in the current project, we will use the surface chemical modification strategies to introduce and engineer intrinsic ferromagnetic properties of inorganic 2D TMCDs while maintaining the pristine 2D lattice framework. With the synergic combination of X-ray absorption fine structure (XAFS) analysis and density functional theoretical (DFT) calculations, the relationship between local structure and magnetic properties under 2D confined structure will be studied. In addition, the coupling of magnetism and electricity namely, magnetoresistance effect, of surface modified 2D TMDCs will also be studied. Through the assembly of the free-standing 2D ultrathin nanosheet into integrated films with transferable properties, the 2D thin film based spintronic devices will be designed.

二维类石墨烯过渡金属硫属化合物比全碳石墨烯具备更多的元素选择和结构优化自由度，对其本征磁性能调控是构筑新一代纳米自旋电子器件的关键。当这类材料剥离达到原子层厚度时，极大的比表面积使得二维材料的表面相成为了材料本征物性的主导相。本项目拟采用表面化学调控方法，在保持材料二维层状拓扑结构基础上，通过表面吸附，表面应力，表面缺陷等化学调控方法，实现纳米片表面电子结构的调整，引入并调控二维过渡金属二硫属化合物材料的本征铁磁性。基于同步辐射精细X射线吸收谱图解析和密度泛函理论计算，研究二维限域下局域结构和磁性能之间的构效关系。在此基础上，进一步探索表面化学改性二维材料的磁性和电阻间耦合产生的磁电阻效应。通过对表面化学改性获得二维超薄结构进行组装和转移，实现基于二维过渡金属硫属化合物超薄磁性结构的自旋电子器件的构筑。

二维固体是指具有单原子层或少数原子层厚度的二维纳米结构材料，近年来以其极高的比表面积和独特的限域电子结构特征吸引了广泛的研究。在本项目实施过程中，项目负责人利用表面化学法对过渡金属硫属化合物二维固体的自旋结构开展了系统的研究，同时拓展了自旋和电子输运，催化性能的研究，取得了系列成果。实现了二维固体自旋结构的表面化学法调控：提出了通过表面掺杂、缺陷、表面吸附和层间范德华力等方法来调控二维固体的自旋结构；进而优化了二维超薄结构在磁、电和催化方面的性能。该项目展现了二维固体在信息和能源相关领域的广泛应用前景。基于以上研究，负责人以第一或通讯作者身份在Nat. Commun., J. Am. Chem. Soc. (2篇), Angew. Chem. Int. Ed. (2篇), Adv. Mater. (2篇), Chem等化学、材料重要期刊发表相关研究论文9篇，应邀为JACS撰写Perspective综述论文。