School of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006, China.
Dalton Trans. 2019 Jan 22;48(4):1314-1321. doi: 10.1039/c8dt04720k.
In this study, the positive effects and dual roles of SiB4 on the dehydrogenation and rehydrogenation performance of the LiBH4-SiB4 system are reported. Characterizations were performed through temperature programmed desorption mass spectrometry (TPD-MS), isothermal kinetics measurements, and XRD and FTIR analyses. For the hydrogen desorption from LiBH4, SiB4 played the role of a catalyst to kinetically facilitate the structural destabilization of LiBH4 and its intermediate phase Li2B12H12. Accordingly, a dehydrogenation capacity of 2.24 at. H/f.u. LiBH4 (close to 10.3 wt% H) was attained at a relative temperature of 350 °C. For hydrogen absorption to generate LiBH4, SiB4 was unexpectedly found to act as a reactant to thermodynamically improve the rehydrogenation process by reacting with LiH under moderate conditions of 10 MPa H2 and 400 °C, and a superior reversible capacity of 2.16 at. H/f.u. LiBH4 was achieved. These experimental results remind us to take into account the explicit role(s) of the employed components during the dehydrogenation and rehydrogenation reactions when designing a desirable LiBH4-based system.
在这项研究中，报告了 SiB4 对 LiBH4-SiB4 体系脱氢和再氢化性能的积极影响和双重作用。通过程序升温脱附质谱（TPD-MS）、等温动力学测量、XRD 和 FTIR 分析进行了表征。对于 LiBH4 的氢解吸，SiB4 起到了催化剂的作用，从而在动力学上促进了 LiBH4 及其中间相 Li2B12H12 的结构失稳。因此，在相对温度为 350°C 时，达到了 2.24 个原子 H/f.u. LiBH4（接近 10.3wt% H）的脱氢容量。对于生成 LiBH4 的氢气吸收，出人意料的是，SiB4 被发现作为反应物在 10 MPa H2 和 400°C 的中等条件下与 LiH 反应，从而在热力学上改善了再氢化过程，实现了 2.16 个原子 H/f.u. LiBH4 的优异可逆容量。这些实验结果提醒我们，在设计理想的 LiBH4 基体系时，在脱氢和再氢化反应中考虑所使用成分的明确作用。
