采用高能球磨制备Ni?25％X(X=Fe,Co,Cu,摩尔分数)固溶体,然后将其掺杂于MgH2体系中.与球磨纯MgH2相比,MgH2/Ni?25％X复合体系初始放氢温度降低近90℃,其中,Ni?25％Co固溶体呈最佳催化效果.球磨MgH2/Ni?25％Co复合体系在300℃、10 min内可释放5.19％(质量分数)氢,而相同条件下,纯MgH2仅释放1.78％(质量分数)氢;更为重要的是,放氢后MgH2/Ni?25％Co复合体系在275℃、3 min内可吸收5.39％(质量分数)氢.MgH2/Ni?25％Co体系优异的吸放氢动力学可归因于其在吸/放氢过程中原位形成Mg2Ni(Co)化合物的催化作用.第一性原理计算表明,掺杂过渡金属原子后,Mg/MgH2体系吸放氢反应能垒显著降低,较好地解释了镍基固溶体催化改善MgH2储氢性能的实验结果.“,”The Ni?25％X (X=Fe, Co, Cu, molar fraction) solid solutions were prepared and then doped into MgH2 through high-energy ball milling. The initial dehydrogenation temperatures of MgH2/Ni?25％X composites are all decreased by about 90 ℃ relative to the as-milled pristine MgH2. The Ni?25％Co solid solution exhibits the most excellent catalytic effect, and the milled MgH2/Ni?25％Co composite can release 5.19 wt.％ hydrogen within 10 min at 300 ℃, while the as-milled pristine MgH2 can only release 1.78 wt.％ hydrogen. More importantly, the dehydrogenated MgH2/Ni?25％Co composite can absorb 5.39 wt.％ hydrogen at 275 ℃ within 3 min. The superior hydrogen sorption kinetics of MgH2/Ni?25％Co can be ascribed to the actual catalytic effect of in-situ formed Mg2Ni(Co) compounds. First-principles calculations show that the hydrogen absorption/desorption energy barriers of Mg/MgH2 systems decrease significantly after doping with transition metal atoms, which interprets well the improved hydrogen sorption properties of MgH2 catalyzed by Ni-based solid solutions.