基于隧穿电导和表面等离激元“探针”的镁基合金纳米粒子储氢机制研究

The rise of hydrogen economy has promoted the worldwide research and development of hydrogen storage materials. The exploring of new hydrogen storage materials has attracted much attention from scientific community. Among the various hydrogen storage materials, Mg-based hydrides are one of the most promising hydrogen storage materials to meet the application requirements of hydrogen storage system because of their relatively high storage capacity, abundance, and low cost. In this project, Mg-based alloy nanoparticles and its assembled nanostructures are controllably prepared by gas phase aggregation method. Their hydrogen storage properties are studied by means of in situ monitoring electron tunneling as well as plasmonic spectroscopy. Based on the experimental study, the effects of composition of the alloy, size of the nanostructure and phase structure on the hydrogen storage performance, as well as the action mechanism of nanocrystallization on thermodynamics and kinetics of hydrogenation and dehydrogenation will be investigated. The catalytic effect of second phase on hydrogen storage reaction of matrix phase and the synergistic effect of multi-component phase structure in the multicomponent Mg-based alloy nanoparticles will be explored. We will try to understand how the hydrogen storage properties of Mg-based alloy nanoparticles are influenced by their microstructure and will establish a theoretical model about this. Moreover, the possibility and mechanism of dehydrogenation induced by localized surface plasmon resonance are investigated in order to improve the hydrogen desorption properties. This project is of great theoretical significance and practical application value to explore new low dimensional hydrogen storage materials and deeply understand its hydrogen storage mechanism.

氢经济的兴起推动了全球范围内的储氢材料研究热潮，寻找新型储氢材料备受科学界的广泛关注。在众多储氢材料中，镁基材料由于储氢容量高、资源丰富、成本低等优势被认为是最有望满足储氢系统应用要求的储氢材料之一。本项目采用气相聚集法可控制备镁基合金纳米粒子及其组装结构，以原位的隧穿电导和等离激元共振谱监测为表征手段，研究其储氢性质。通过实验研究，揭示纳米尺度下合金成分、纳米结构尺寸、多元相结构等诸多因素对储氢性能的影响，探讨纳米化对吸/放氢热力学与动力学性质的作用机理，阐明多组元镁基合金纳米粒子中第二相对基体相储氢反应的催化作用以及多元相之间的协同作用。掌握镁基合金纳米粒子的储氢性能受微观结构的影响规律，并建立相关理论模型。探索局域表面等离激元共振诱导放氢反应的可能性及作用机制，以期改善镁基合金纳米粒子的放氢性能。本项目对于探索新型低维储氢材料体系并深入认识其储氢机制具有重要的理论意义和实际应用价值。

镁(Magnesium，Mg)是唯一超过美国能源部对氢动力汽车储氢要求的金属储氢材料，此外，Mg基储氢成本低廉，是公认的最有前景的金属储氢材料之一。但是，Mg基储氢材料仍然存在吸放氢热力学温度过高和反应动力学性能较差两个方面的问题。因此，改善Mg基储氢材料的吸放氢热动力学性能具有重要科学意义与实用价值。在本课题的研究中，利用自主研发的双靶磁控等离子体气体聚集源并结合团簇束流技术成功制备了Mg基二元合金纳米粒子及其组装材料，并将镁/钯合金纳米粒子作为重点研究对象，在吸放氢行为规律与性能调控方面展开了细致的研究工作，主要的研究进展如下：（1）以双靶共溅射磁控等离子体气体聚集源为工具，结合团簇束流技术，实现了4~60nm的Mg基纳米粒子的可控制备；通过双靶共溅射和单独溅射两种方式获得了Mg6Pd合金纳米粒子与Pd点缀的Mg纳米粒子；（2）建立了一套通过光学法原位表征Mg基纳米粒子吸放氢行为的研究手段和实验装置；（3）探讨了Mg基纳米粒子吸放氢的热动力学行为，并且通过纳米化手段将吸放氢温度降低至150℃，通过Pd的点缀降低了表观活化能，显著提升了Mg基纳米粒子吸放氢的动力学性能，使得Mg基纳米粒子吸放氢反应时间降低至10s以内。本项目探索了镁基合金纳米粒子的可控制备方法，通过引入钯元素调控了镁基纳米粒子的吸放氢热动力学性能，这些研究对于深化认识Mg基纳米粒子吸放氢机制具有普遍意义，为基于金属储氢以及氢气传感提供了理论参考可行的优化性能方案与理论参考。