摘要
4MgH 2 -LiAlH 4 composite exhibits reduced over-high thermal stability and enhanced de/re-hydrogenation kinetics in previous work. However, de/re-hydrogenation temperatures are still higher than the requirement of mobile fuel cell system. In this case, two-dimension lamellar Ti 3 C 2 was introduced into the 4MgH 2 -LiAlH 4 composite. The de-hydrogenation onset temperature of 4MgH 2 -LiAlH 4 -Ti 3 C 2 composite is decreased by 64 K and 274 K from 4MgH 2 -LiAlH 4 and as-milled MgH 2 , respectively. Its de-hydrogenation activation energy value is reduced by 47.8 kJ mol −1 from 176.2 kJ mol −1 of 4MgH 2 -LiAlH 4 . The re-hydrogenation activation energy (65.7 kJ mol −1 ) of 4MgH 2 -LiAlH 4 -Ti 3 C 2 is also lowered by 33.5 kJ mol −1 from 4MgH 2 -LiAlH 4 (99.2 kJ mol −1 ). Further study indicates that Ti 3 C 2 partially decomposed itself during ball milling and was completely transformed to metallic Ti and carbon during de-hydrogenation. The identified TiH 1.942 indicates that in-situ formed Ti should react with 4MgH 2 -LiAlH 4 system and slightly destabilize the system. For this system, de-hydrogenation enthalpies in three stages (65.9 kJ mol −1 H 2 −1 , 70.6 kJ mol −1 H 2 -1 and 74.3 kJ mol −1 H 2 −1 , respectively) are all lower than as-milled MgH 2 (76.2 kJ mol −1 H 2 −1 ). It means that introducing Ti 3 C 2 into 4MgH 2 -LiAlH 4 not only improves the reaction kinetics but also lowers its over-high thermal stability.
| 源语言 | 英语 |
|---|---|
| 页（从-至） | 178-187 |
| 页数 | 10 |
| 期刊 | Chemical Physics |
| 卷 | 522 |
| DOI | |
| 出版状态 | 已出版 - 1 6月 2019 |