(1. 长沙理工大学工程车辆轻量化与可靠性技术湖南省高校重点实验室，长沙 410114；
2. 长沙理工大学能源高效清洁利用湖南省高校重点实验室，长沙 410114；
3. 湖南大学汽车车身先进设计制造国家重点实验室，长沙410082)
摘 要: 选取石墨与石墨烯两种碳材料作为掺杂剂，采用机械球磨方法分别制备纯MgH2、MgH2-10%石墨(质量分数)及MgH2-10%石墨烯3种储氢体系，并结合XRD、SEM、DSC-TG实验表征手段与具有原子尺度模拟能力的第一性原理计算方法，研究碳材料掺杂对MgH2释氢性能的影响及其微观机理。结果表明：微量石墨与石墨烯的掺杂使得MgH2释氢温度得到降低，相比之下，石墨烯掺杂效果较为明显，其掺杂致使MgH2初始释氢温度降低近33℃。此外，石墨与石墨烯掺杂均有助于抑制球磨过程中颗粒的团聚，起到结构限域的作用，促进MgH2快速释氢。第一性原理计算表明，碳材料掺杂改善MgH2释氢性能的内在原因在于其掺杂削弱了Mg—H间的键强，降低了H原子从MgH2基体中释放时的解离能。
关键字: MgH2；碳材料；掺杂；释氢性能；第一性原理
（1. Key Laboratory of Lightweight and Reliability Technology for Engineering Vehicle, Education Department of Hunan Province, Changsha University of Science and Technology, Changsha 410114, China;
2. Key Laboratory of Efficient and Clean Energy Utilization, Education Department of Hunan Province,
Changsha University of Science and Technology, Changsha 410114, China;
3. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China）
Abstract:The pure MgH2, MgH2-10% graphite (mass fraction) and MgH2-10% graphene hydrogen storage systems were prepared by mechanical ball-milling technology with two kinds of carbon materials such as graphite and graphene as the dopants. Using the XRD, SEM, DSC-TG experimental testing methods in combination with the first-principle calculations with the atomic scale simulation ability, the influence of carbon materials doping on the dehydrogenation properties of MgH2 and the micro-mechanism were investigated. The results show that the doping of a little graphite or graphene lowers the dehydrogenation temperature of MgH2. By contrast, the doping effect of graphene is relatively better and it lowers the initial dehydrogenation temperature of MgH2 by about 33 ℃. Besides, graphite and graphene play the role of structural confinement since they inhibit powder agglomeration during ball-milling, which is beneficial toaccelerating hydrogen desorption. The first-principle calculations show that the doping of carbon materials weakens the bonding strength between Mg and H, which results in the reduced dissociation energy of H atoms from MgH2 matrix. This may be the intrinsic reason for improving dehydrogenation properties of MgH2 with carbon materials doping.
Key words: MgH2;carbon material; doping; dehydrogenation property; first-principle
