University College London, Department of Chemistry, London WC1E 0AJ, UK.
Phys Chem Chem Phys. 2011 Oct 21;13(39):17683-8. doi: 10.1039/c1cp22408e. Epub 2011 Sep 7.
A significant improvement in the dehydrogenation kinetics of the (LiNH(2) + LiH) system was obtained upon doping with elemental Si. Whilst, complete dehydrogenation of the (LiNH(2) + LiH) system requires more than 2 h, the time required for full dehydrogenation was reduced to less than 30 min by doping with elemental Si. It is observed that Si thermodynamically destabilises the system through the formation of novel intermediate phases resulting from the reaction of Si with both LiNH(2) and LiH. Such intermediate phases are also believed to enhance reaction kinetics by providing a path for accelerated dehydrogenation and the rapid release of hydrogen at the early stages of the reaction. It is believed that the dehydrogenation kinetics of the (LiNH(2) + LiH) system, which is controlled by the diffusion of H(-) from LiH and H(+) from LiNH(2), becomes independent of diffusion upon Si addition due to an enhanced concentration gradient in reactive ionic species.
掺杂元素硅可显著提高（LiNH₂+LiH）体系的脱氢动力学。虽然，（LiNH₂+LiH）体系完全脱氢需要 2 个多小时，但掺杂元素硅后完全脱氢的时间缩短至 30 分钟以内。研究发现，Si 通过与 LiNH₂和 LiH 反应形成新型中间相，使体系热力学不稳定。这些中间相也被认为通过提供加速脱氢和在反应早期快速释放氢气的途径来增强反应动力学。据信，（LiNH₂+LiH）体系的脱氢动力学受 H(-)从 LiH 和 H(+)从 LiNH₂的扩散控制，添加 Si 后由于反应离子物种的浓度梯度增强，扩散变得独立。
