轻金属硼氢化物储氢材料催化掺杂与纳米化改性的原位分析及机理研究

Light metal borohydrides, such as LiBH4, have recently attracted a great research interest in hydrogen storage due to the extremely high hydrogen storage capacity. However, the stable thermodynamics and sluggish kinetics hindered its practical applications. To ease these issues, doping transition metal compounds and nano-confinement were applied and proved as the most effective ways to improve the hydrogen storage properties. However, the related enhancing mechanisms are still enigmatic and controversial due to the scarcity of solid experimental evidences. Here, we propose to utilize the in situ techniques, such as in situ environmental transmission electron microscope (ETEM), in situ X-ray diffraction (XRD), in situ Fourier transform infrared (FTIR) spectra and in situ Raman spectra, to probe the dehydrogenation processes of the catalytic doped and the nano-confined LiBH4. A systematic investigation will be conducted on the phase transformation reactions, intermediate products, the interface structure characteristic, efficient catalytic components for catalytic doped LiBH4 system during the dehydrogenation. As for the nano-confined LiBH4, controllable synthesis technology, as well as the size effect on the hydrogen absorption/desorption thermodynamics, kinetics and cycling properties of LiBH4 will be developed. By employing density functional theory (DFT) calculations, these two ways of improvements for hydrogen storage will be compared and their modification mechanism will be drawn exactly. Based on the above investigations, a synergistic effect of catalysis and nanoconfinement will be explored. These studies will supply the experimental and theoretical basis data to the further development and application for novel complex borohydrides.

以LiBH4为代表的轻金属配位硼氢化物是目前高容量储氢材料的研究热点，但存在热力学性质过于稳定、吸放氢动力学性能较差等关键问题。催化掺杂和纳米限域（纳米化）是轻金属硼氢化物储氢材料的两种重要改性方法，但详细改性机理仍不清晰。针对上述问题，本项目提出利用原位环境透射电镜、X射线衍射、傅里叶变换红外吸收光谱、拉曼光谱等实时分析技术，对催化掺杂改性和纳米限域改性的轻金属硼氢化物储氢体系进行原位分析研究，查明催化掺杂改性体系放氢过程中各阶段的相变反应与中间产物、界面结构特征、有效催化组元等信息，掌握纳米限域改性体系的高效可控合成技术以及纳米尺寸效应对LiBH4吸放氢热力学、动力学和循环性能的影响规律；结合第一性原理理论计算，准确揭示这两种改性方式的详细作用机理，并探索两者的协同改性作用。获取必要的基础数据及信息，为此类轻金属硼氢化物新型储氢材料的后续应用研究提供理论和实验依据。

本项目利用原位环境透射电镜、X射线衍射、傅里叶变换红外吸收光谱、拉曼光谱以及同步辐射等多种分析技术，对催化掺杂改性和纳米限域改性的轻金属硼氢化物储氢体系进行了原位/准原位分析研究，查明了系列催化剂（h-BN、NbCl5/h-BN、NbH@h-BN、FeCl2、CoCl2、NiCl2、Fe/Co/Ni@C和Ni@g-C3N4）掺杂改性体系放氢过程中各阶段的相变反应与中间产物、界面结构特征、有效催化组元，掌握了多种框架材料（ZTC、ZTC-750、CAS-4，CAS-13和CAS-25）纳米限域轻金属硼氢化物储氢体系的可控合成技术以及尺寸效应对LiBH4吸放氢热力学、动力学和循环性能的影响规律；结合理论计算，揭示了上述两种改性方式对金属硼氢化物储氢材料的改性作用机理，并系统研究了LiBH4@MC-NbF5和LiBH4@NbF5-CMK-3复合体系可逆储氢性能和微观结构演变关系，探索了两者的协同改性作用。本项目已完成了预定的研究任务，并获取大量相关的基础数据及信息，为此类轻金属硼氢化物新型储氢材料的后续应用研究提供理论和实验依据。结合本项目研究任务，共培养博士毕业生3名、硕士毕业生1名，目前在读博士生1名、硕士生1名；研究成果申请国家发明专利5项，其中2项已授权；发表SCI收录论文21篇，全部标注了本基金项目的资助号。