Controllable fabrication of Ni-based catalysts and their enhancement on desorption properties of MgH2
Controllable fabrication of Ni-based catalysts and their enhancement on desorption properties of MgH2
复制标题
镍基催化剂的可控制备及其对MgH2解吸性能的增强
DOI：
10.1016/j.jallcom.2017.05.011
复制
发表时间：
2017
影响因子：
6.2
通讯作者：
Li Liquan
中科院分区：
文献类型：
--
作者：
Zhang Jiguang;Li Shenyang;Zhu Yunfeng;Lin Huaijun;Liu Yana;Zhang Yao;Ma Zhongliang;Li Liquan
寻找有效的催化剂是提高金属基储氢材料储氢性能，特别是储氢动力学研究的重要课题。采用改进的湿化学法控制Ni形貌，研究了Ni形貌（包括尺寸和形状）对MgH2脱附性能的影响。将合成的Ni基催化剂引入MgH2中，发现其具有明显的脱附行为，证明了催化相的形貌依赖效应的存在。其中，石墨烯片（GS）负载Ni（Ni6GS4）的催化性能最好，MgH2开始脱附温度降低到225 °C（未掺杂MgH2在308 °C开始脱附），饱和脱氢量为6.74wt%。储氢动力学的显着增强归因于不仅初始Ni活性相的相对小的颗粒尺寸，而且其良好的分散分布状态和球磨过程中的进一步细化。此外，我们认为GS的良好分散能力在将Ni纳米颗粒彼此分离和防止MgH2颗粒聚集方面特别重要，从而导致期望的循环性能。实验结果表明了金属基催化剂的形状和尺寸对MgH2体系的影响，为设计轻质、超细、均匀分布和高活性的纳米结构催化剂提供了指导或策略。
Searching for effective catalysts is one of the most attractive subjects to enhance the hydrogen storage properties, especially the sorption kinetics of the metal-based hydrides. The effect of the Ni morphology (including size and shape) on the desorption performance of MgH2was studied in the paper, in which a modified wet chemical route was used to control the morphology of Ni. By introducing the as-synthesized Ni-based catalysts into MgH2, a well-distinguished desorption behavior was found, evidencing the existence of the morphology-dependent effect of the catalytic phase. Among them, graphene sheets (GS) supported Ni (Ni6GS4) exhibited the best catalytic performance with a lowered MgH2onset desorption temperature of 225 °C (the undoped MgH2initiated to desorb hydrogen at 308 °C) and a saturated hydrogen desorption capacity of 6.74 wt%. The significant enhancement of the hydrogen storage kinetics was ascribed to not only the relative small particle size of the initial Ni active phase but also its well-dispersed distribution state and further refinement during ball milling. In addition, we believe that the good dispersive ability of GS was of particular importance in separating the Ni nanoparticles from each other and preventing aggregating of the MgH2particles, leading to a desirable cyclic performance. Our results have experimentally shown the influence of shape and size of metal-based catalysts on the MgH2system, providing guideline or strategy designing nanostructured catalysts with light weight, ultra-fine particle size, well-formed distribution and high activity.