Mg-Ti-Cr复合纳米颗粒的制备及其储氢性能

Synthesis and Hydrogen Storage Properties of the Mg-Ti-Cr Nanocomposite

利用氢气等离子体法成功制备Mg纳米颗粒和Cr_(1.8)TiH_(5.3)-Cr复合纳米颗粒,然后球磨混合Mg和Cr_(1.8)TiH_(5.3)-Cr得到Mg-5wt.%(Cr_(1.8)TiH_(5.3)-Cr)复合纳米颗粒样品。其中Mg颗粒的平均粒径为166 nm,Cr_(1.8)TiH_(5.3)-Cr颗粒尺寸大约为15 nm并均匀地镶嵌在Mg颗粒表面。该复合纳米颗粒在623 K下,5 min内吸氢量达到4.6wt.%;573 K时,5 min内吸氢4.0 wt.%。673 K时,放氢速率较快,5 min内放氢量达到5.1 wt.%。其吸氢激活能为48.5 kJ/mol,Cr_(1.8)TiH_(5.3)-Cr纳米颗粒的添加以及Mg颗粒尺寸的纳米化效应在一定程度上降低了吸氢激活能,改善了其吸氢动力学性能。

The Mg and Cr_（1.8）TiH_（5.3）-Cr nanoparticles（NPs） are successfully prepared by hydrogen plasma-metal reaction method, and then Mg-5wt.%（Cr_（1.8）TiH_（5.3）-Cr） nanocomposite is prepared by ball milling. The spherical Cr_（1.8）TiH_（5.3）-CrNPs of about 15 nm are uniformly dispersed on the surface of Mg particles（166 nm）. The nanocomposite quickly absorbs 4.6 wt.% H_2 in 5 minutes at 623 K and 4.0 wt.% H_2 in 5 minutes at 573 K. It can also quickly release 5.1 wt.% H_2 in 5 minutes at 673 K. The apparent activation energy for hydrogen absorption is 48.5 kJ/mol. The reduced activation energy and the enhanced hydrogenation kinetics are attributed to the catalytic effect of Cr_（1.8）TiH_（5.3）-CrNPs and the nanosizing effect of Mg particles.