二维金刚石纳米膜的结构演化及物性的理论与实验研究

In recent years, the two dimensional (2D) diamond nanosheets have become one of most interesting topics in the field of diamond. However, only a few works have been reported on this issue. In comparison with traditional 0-dimentional and one-dimentional diamond nanostructures, the structure and properties of 2D diamond nanosheets with significant surface and quantum size effects are strongly dependent on their orientation, number of layer, doping and surface functionalization. For this project, the first-principles calculations are proposed to deeply and systematically study the structural stability and evolution of the 2D diamond nanosheets related to the factors of crystalline orientation, layer number, doping, surface modification, etc. By analyzing the band structure, electron and spin density of state (DOS), it is expected to reveal the unique structure-related electronic and magnetic properties of the 2D diamond nanosheets. Experimentally, by pulse laser ablation and/or hydrogen plasma treatment, we try to synthesize the atomically thick 2D diamond nanosheets with large area. The characterizations and the examinations of the optical, electronic, magnetic prosperities of the 2D nanosheets would be carried out by means of various methods. The combination of the theoretical and experimental results would reveal novel structures and properties with respect to that for bulk diamond and the other types of diamond nanostructures. The implementation of this project will provide new theoretical and experimental data for developing the low dimensional diamond and expanding the research fields of diamond for further applications.

二维金刚石纳米膜是近几年来金刚石领域新的研究方向，具有重要的科学研究价值，而相关研究报道很少。不同于传统的零维和一维纳米金刚石，二维金刚石纳米膜的结构和性质对其取向、层数、掺杂和表面功能化等具有强烈的依赖性，并且出现强的表面效应和量子尺寸效应。本项目拟利用基于密度泛函理论的第一性原理计算，深入、系统地研究取向、层数、掺杂、表面修饰等因素对二维金刚石纳米膜的结构稳定性和演化的影响，并通过分析能带结构、电子态密度和自旋磁矩等，获得与结构相关的光学、电学及磁学性质变化规律。利用激光轰击剥离金刚石单晶及氢等离子体处理石墨烯等制备方法，获得一定尺寸、原子级厚度的二维金刚石纳米膜。通过多种实验手段对所制备的材料进行表征及性能测试，结合理论计算结果，揭示其不同于金刚石体材料和其他纳米材料的结构和性质。本项目的实施，将为发现金刚石相关的新现象及拓展金刚石的研究领域提供新的理论依据和实验数据。

二维金刚石纳米膜是近几年来金刚石领域新的研究方向，本项目组是国际上最早开展相关工作的单位之一。不同于传统的零维和一维纳米金刚石，二维金刚石纳米膜的结构和性质对其取向、层数和表面功能化等具有强烈的依赖性，并且出现强的表面效应和量子尺寸效应，具有重要的科学研究和应用价值。本项目利用基于密度泛函理论的第一性原理计算，系统地研究(100)、(110)和(111)取向二维金刚石纳米膜随着层数的结构演化，并在二维金刚石纳米膜表面进行氢化或氟化处理，及掺杂不同元素（硅、硅-空位等），并通过分析能带结构、电子态密度和自旋磁矩等，获得相关的光学、电学及磁学性质变化规律，揭示不同于体金刚石和其它纳米结构材料的特性。利用CALYPSO晶体结构预测方法系统预测了金刚石（111）表面生长的菱形硅烯超结构和稳定的二维单层Bx/2Cx/2N1-x (0 < x < 1)化合物。利用激光轰击剥离金刚石单晶及等离子体处理石墨烯等制备方法，初步获得一定尺寸、原子级厚度的二维金刚石纳米膜。将纳米金刚石用于锂离子电池负极及燃料电池电解质，有效提高了锂离子电池及燃料电池的性能，扩展了低维金刚石的应用。本项目的实施中，发表SCI论文16篇，申请发明专利5项，获授权发明专利4项。本项目的完成，对于发现金刚石相关的新现象及拓展金刚石的研究领域提供了重要的理论依据和实验数据。