Xiao Xuezhang, Liu Zhe, Saremi-Yarahmadi Sina, Gregory Duncan H
WestCHEM, School of Chemistry, University of Glasgow, Joseph Black Building, Glasgow G12 8QQ Scotland, UK.
Phys Chem Chem Phys. 2016 Apr 21;18(15):10492-8. doi: 10.1039/c5cp07762a. Epub 2016 Mar 31.
A magnesium hydride composite with enhanced hydrogen desorption kinetics can be synthesized via a simple wet chemical route by ball milling MgH2 with LiCl as an additive at room temperature followed by tetrahydrofuran (THF) treatment under an Ar atmosphere. The as-synthesized composite comprises ca. 18 mass% orthorhombic γ-MgH2 and 80 mass% tetragonal β-MgH2 as submicron-sized particles. The β-/γ-MgH2 nanocomposite exhibits a dehydrogenation capacity of 6.6 wt% and starts to release hydrogen at ∼260 °C; ca. 140 °C lower than that of commercial MgH2. The apparent activation energy for dehydrogenation is 115 ± 3 kJ mol(-1), which is ca. 46% lower than that of commercial MgH2. Analysis suggests that the meta-stable γ-MgH2 component either directly dehydrogenates exothermically or first transforms into stable β-MgH2 very close to the dehydrogenation onset. The improved hydrogen release performance can be attributed both to the existence of the MgH2 nanostructure and to the presence of γ-MgH2.
一种具有增强的氢解吸动力学的氢化镁复合材料可以通过一种简单的湿化学路线合成，即在室温下将MgH₂与作为添加剂的LiCl进行球磨，然后在氩气气氛下用四氢呋喃（THF）处理。所合成的复合材料包含约18质量%的正交晶系γ-MgH₂和80质量%的四方晶系β-MgH₂作为亚微米尺寸的颗粒。β-/γ-MgH₂纳米复合材料表现出6.6 wt%的脱氢容量，并在约260°C开始释放氢气；比商业MgH₂低约140°C。脱氢的表观活化能为115±3 kJ mol⁻¹，比商业MgH₂低约46%。分析表明，亚稳的γ-MgH₂组分要么直接放热脱氢，要么在非常接近脱氢起始点时首先转变为稳定的β-MgH₂。氢释放性能的改善可归因于MgH₂纳米结构的存在以及γ-MgH₂的存在。
