Facile Synthesis of Carbon Supported Nano-Ni Particles with Superior Catalytic Effect on Hydrogen Storage Kinetics of MgH2
Facile Synthesis of Carbon Supported Nano-Ni Particles with Superior Catalytic Effect on Hydrogen Storage Kinetics of MgH2
复制标题
轻松合成碳负载纳米镍颗粒，对 MgH2 储氢动力学具有优异的催化效果
DOI：
10.1021/acsaem.7b00266
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发表时间：
2018-03-01
影响因子：
6.4
通讯作者：
Li, Liquan
中科院分区：
文献类型：
--
作者：
Ma, Zhongliang;Zhang, Jiguang;Li, Liquan
金属纳米催化是提高氢化镁储氢性能的有效方法，而负载纳米金属的基质材料可以进一步提高催化效果。本工作采用焙烧法制备了碳负载纳米镍(Ni@C)，并将其掺杂到氢氧化镁中，改善了催化剂的脱氢/再加氢动力学。结果表明，Ni在碳基中分布均匀，颗粒细小，对MgH2-5wt%Ni@C的吸放氢有较好的催化作用，在187℃开始放氢，比球磨前低113℃。而且，在300摄氏度下，S只需要500分钟就可以完全解吸氢气，在相同的脱氢条件下，比磨出的氢化镁快3000 S。根据Kisinger的方法，MgH_2-5wt%Ni@C的表观脱附活化能为66.5+/-1.8kJ摩尔(-1)，比球磨前的表观活化能低79.9kJ摩尔(-1)。循环实验表明，在275℃下循环10次，吸放氢容量保持率分别为91%和93%。透射电子显微镜分析表明，在吸放氢循环过程中，部分Ni转变为Mg2NiH4/Mg2Ni。
Metal nanocatalysis is an effective method to enhance the hydrogen storage properties of magnesium hydride (MgH2), and the catalytic effect can be further improved by a matrix material supported nanometal. In this work, carbon supported nano-Ni (Ni@C) was synthesized by calcination of dimethylglyoxime dinickel chelate, and then it was doped into MgH2 to improve the de/rehydrogenation kinetics. This shows that the homogeneously distributed Ni with refined particle size in carbon base leads to superior catalytic effects on hydrogen absorption/desorption of MgH2-5 wt % Ni@C. The MgH2-5 wt % Ni@C starts to desorb hydrogen at 187 degrees C, which is 113 degrees C lower than that of as-milled MgH2. Moreover, it takes only 500 s to thoroughly desorb hydrogen at 300 degrees C, which is 3000 s faster than as-milled MgH2 under the same dehydrogenation conditions. According to the Kissinger's method, the apparent activation energy for desorption of the MgH2-5 wt % Ni@C is 66.5 +/- 1.8 kJ mol(-1), which is about 79.9 kJ mol(-1) lower than that of as-milled MgH2. Cycling experiments show that the capacity retentions of hydrogen absorption and desorption after 10 cycles at 275 degrees C are 91% and 93%, respectively. Transmission electron microscope analysis shows that part of Ni transformed to Mg2NiH4/Mg2Ni during hydrogen absorption/desorption cycles.