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首页> 外文期刊>RSC Advances >Synergistically thermodynamic and kinetic tailoring of the hydrogen desorption properties of MgH2 by co-addition of AlH3 and CeF3
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Synergistically thermodynamic and kinetic tailoring of the hydrogen desorption properties of MgH2 by co-addition of AlH3 and CeF3

机译：通过共同添加AlH3和CeF3对MgH2的氢解吸特性进行协同热力学和动力学调整

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摘要

MgH2 possesses a high hydrogen capacity and excellent reversibility. However, the high thermal stability and slow sorption kinetics retard its practical application as an on-board hydrogen storage material. In this work, AlH3 and CeF3 were introduced into Mg-based materials for the purpose of improving both the thermodynamic and the kinetic properties of MgH2. DSC-TG analysis shows that the onset hydrogen desorption temperature of MgH2 can be synergistically reduced by 86 degrees C through the co-addition of 0.25AlH(3) and 0.01CeF(3). Isothermal desorption measurements demonstrate that the co-addition of AlH3 and CeF3 significantly enhances the hydrogen desorption kinetics of MgH2 with the absence of the induction period in the initial stage and the acceleration of the hydrogen desorption process. In addition, this co-doped MgH2 shows very good cycling stability at 300 degrees C with a 1 h capacity of 3.5 wt% and a 3 h capacity of 4.5 wt%. Structural analysis by XRD measurements indicates that during the hydrogen desorption process, MgH2 may react with Al (generated from the in situ decomposition of AlH3) to form Mg solid solution and Mg17Al12, which contribute to the thermodynamic improvement of the Mg-based material. In addition, MgH2 may also react with CeF3 to form MgF2 and CeH2-3, which act both as hydrogen diffusion gateways and as an impediment to the grain growth of MgH2 during hydrogen sorption cycling, thus improving the hydrogen desorption kinetics and the cycling stability of MgH2. Finally, it was found that the presence of AlH3 kinetically helps CeF3 to exert its positive effect on the hydrogen desorption properties of MgH2. This work provides a method for simultaneously tailoring the thermodynamic and kinetic properties of MgH2 by the synergistic addition of metal hydride and rare earth fluoride.
机译：MgH2具有高氢气容量和出色的可逆性。然而，高的热稳定性和缓慢的吸附动力学阻碍了其作为车载储氢材料的实际应用。在这项工作中，AlH3和CeF3被引入到Mg基材料中，以同时改善MgH2的热力学和动力学特性。 DSC-TG分析表明，通过共同添加0.25AlH（3）和0.01CeF（3），可以将MgH2的起始氢脱附温度降低86度。等温解吸测量表明，AlH3和CeF3的共添加显着增强了MgH2的氢解吸动力学，而在初始阶段没有诱导期，并且没有加速氢解吸过程。另外，这种共掺杂的MgH 2在300℃下显示出非常好的循环稳定性，其1小时容量为3.5重量％，而3小时容量为4.5重量％。 XRD测量的结构分析表明，在氢解吸过程中，MgH2可能与Al（由AlH3的原位分解产生）反应形成Mg固溶体和Mg17Al12，这有助于改善Mg基材料的热力学。此外，MgH2还可与CeF3反应形成MgF2和CeH2-3，它们既充当氢扩散通道，又阻碍了MgH2在氢吸附循环过程中的晶粒长大，从而改善了Hg的氢解吸动力学和循环稳定性。硫酸镁最后，发现AlH3的存在在动力学上有助于CeF3对MgH2的氢解吸性能发挥积极作用。这项工作提供了一种通过协同添加金属氢化物和稀土氟化物来同时调整MgH2热力学和动力学特性的方法。

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