具有18电子结构的Mg_2CoH_5纳米晶制备及其储氢性能研究

Preparation and Hydrogen Storage Properties of Mg_2CoH_5 Nanocrystals with 18-Electrons Structure

本文研究了Mg2CoH5纳米晶的制备及其储氢性能。在室温和氩气气氛下,以MgH2和纳米Co为原料,采用球磨法制备了Mg2CoH5纳米晶。对所制备Mg2CoH5的组成、结构和形貌进行了表征,并且对Mg2CoH5的储氢性能进行了研究。实验结果表明,通过该种方法制备了纯度较高(产物纯度为79%)的四方结构Mg2CoH5纳米晶,其形貌呈球形且分布较均匀,最频粒径为80 nm。制备的Mg2CoH5纳米晶具有较低的活化能和较好的吸放氢动力学性能,其放氢的脱附焓和脱附熵分别为-115.0 kJ.mol-1H2和-193.6.1 J.mol-1.K-1H2。再氢化时,在543 K时仅7 min内其吸氢量就达到1.5wt%。

This paper reports on the preparation of Mg2CoH5 nanocrystals and their hydrogen storage properties. Mg2CoH5 nanocrystals have been synthesized by mechanical ball-milling the mixture of MgH2 and Co nanopartieles at room temperature under an argon atmosphere. The crystal structure, morphologies, and hydrogen storage properties of the as-prepared Mg2CoH5 nanocrystals are investigated. The results show that the tetragonal Mg2CoH5 nanocrystals （79%） are obtained by a ball-milling method at room temperature. The as-prepared Mg2CoH5 nanoerystals present a spherical shape with a well-proportioned particle size distribution around 80nm. Mg2CoH5 nanocrystals show fast absorption/desorption kinetics. The desorption enthalpy and entropy forMg2CoH5are -115.0 kJ.molq H2 and -193.6.1 J.mol-l.K-1H2, respectively. At 543 K,the hydrogen-desorbed sample canabsorb about 1.5wt% hydrogen in 7 min only.