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采用高能球磨技术制备了MgH_2、MgH_2-Graphene、MgH_2-Ni、MgH_2-Graphene-Ni几种不同储氢体系,采用XRD、SEM、DSC等检测手段表征了不同体系的物相组成、微观形貌及释氢性能,系统研究了Graphene与Ni单独、复合掺杂对MgH_2释氢性能的影响及机理。结果表明:Graphene单独掺杂致使MgH_2体系初始释氢温度降低了近33℃,其原因在于球磨过程中Graphene对MgH_2颗粒起到结构限域作用,使其颗粒细化且尺寸均匀。Ni单独掺杂致使MgH_2体系初始释氢温度大幅度降低,降低了136℃,其原因在于部分Ni原子固溶进MgH_2基体,导致其晶格变形、结构稳定性降低。而Graphene与Ni复合掺杂时,其掺杂顺序对MgH_2体系释氢性能具有显著影响:当Graphene与Ni同时掺杂时,由于Graphene对MgH_2颗粒的包覆缓冲作用,致使Ni原子难以固溶进MgH_2基体,体系初始释氢温度并未降低;而先掺杂Ni、后掺杂Graphene时,则很好地实现了Ni原子固溶与Graphene结构限域的双重效应,使得MgH_2体系的初始释氢温度进一步降低,降低了175℃。
Several different hydrogen storage systems, MgH_2-Graphene, MgH_2-Ni and MgH_2-Graphene-Ni, were prepared by high-energy ball milling. The phase composition, morphology and morphology of the systems were characterized by XRD, SEM and DSC. Hydrogen evolution performance, the systematic study of Graphene and Ni alone, composite doping MgH_2 hydrogen evolution performance and mechanism. The results showed that the initial hydrogen evolution temperature of MgH 2 system decreased by nearly 33 ℃ due to Graphene doping alone. The reason for this is that Graphene plays a structural limiting role on MgH 2 during ball milling, resulting in grain refinement and uniform size. The reason for the initial hydrogen release temperature of MgH 2 system decreased greatly by Ni doping is 136 ℃, which is due to some Ni atoms solid solution into MgH 2 matrix, which leads to the lattice deformation and structural stability decrease. When Graphene is doped with Ni, its doping order has a significant effect on the hydrogen evolution performance of MgH_2 system: when Graphene and Ni are doped at the same time, the coating and buffering effect of Graphene on MgH_2 particles makes it difficult for Ni atoms to dissolve in solution MgH_2 matrix, the initial hydrogen release temperature did not decrease. When Ni was first doped and then Graphene was doped, the double effect of Ni atom and Graphene structure was well achieved, which made the initial hydrogen release of MgH_2 system The temperature was further reduced by 175 ° C.