Krishnan Gopi, Negrea Raluca F, Ghica Corneliu, ten Brink Gert H, Kooi Bart J, Palasantzas George
Zernike Institute for Advanced Materials and the Materials Innovation Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Nanoscale. 2014 Oct 21;6(20):11963-70. doi: 10.1039/c4nr03885a.
Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various compositions of Mg with Ni, Cu, and Ti, which are interesting combinations of materials for hydrogen storage systems. To achieve this we first demonstrate the synthesis mechanism of Mg-Ni and Mg-Cu NPs, which is well controlled at the single particle level, in order to accomplish multi-shell, alloy and intermetallic structures of interest for hydrogen storage tests. Aberration corrected transmission electron microscopy was carried out to unravel the detailed atomic structure and composition of the bimetallic NPs after production, processing, and hydrogenation. Finally, a simple and effective methodology is proposed for tuning the composition of the Mg-based bimetallic NPs based on the temperature-dependent nucleation behavior of NPs in the gas-phase.
在此，我们报道了富镁双金属纳米颗粒（NPs）卓越的热稳定性，这对储氢技术至关重要。由于两项关键改进，纳米颗粒的稳定性得以增强：（i）在纳米颗粒形成过程中内部无空隙形成（纳米级柯肯达尔效应）；（ii）在高温下镁氢化过程中抑制了镁的蒸发和纳米颗粒的中空化。结果表明，镁基金属双纳米颗粒热稳定性提高的机制是在蒸发发生之前形成了MgH₂氢化物。对镁与镍、铜和钛的各种组成进行了测试，这些是储氢系统中有趣的材料组合。为实现这一点，我们首先展示了Mg-Ni和Mg-Cu纳米颗粒的合成机制，该机制在单颗粒水平上得到了很好的控制，以实现储氢测试中感兴趣的多壳层、合金和金属间化合物结构。在生产、加工和氢化后，进行了像差校正透射电子显微镜观察，以揭示双金属纳米颗粒的详细原子结构和组成。最后，基于气相中纳米颗粒的温度依赖性成核行为，提出了一种简单有效的方法来调整镁基金属双纳米颗粒的组成。
