School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weihai, 264209, China.
Phys Chem Chem Phys. 2010 Sep 28;12(36):10942-9. doi: 10.1039/b921924b. Epub 2010 Jul 26.
We report a study of the influence of Ti and Ni dopants on the stability and bonding interactions of LiAlH(4) using the first-principles method. Both the Ti and the Ni prefer to occupy an interstitial site in the LiAlH(4) owing to lower occupation energies estimated from the total energy calculations. Calculations show that the bonding interactions between the Al and the H atoms within the [AlH(4)] groups were significantly reduced by the dopants, and both the stability and the geometry of the [AlH(4)] group were distorted in the doped LiAlH(4) systems. However, Ti and Ni use different mechanisms to improve the dehydrogenation properties of LiAlH(4). The Ti dopant tends to interact with the Al atom in its neighbouring [AlH(4)] to 'free' the H atoms from these [AlH(4)] groups. The effect of Ni dopant on the stability and the bonding interactions of the LiAlH(4) is due to the induction of the Ni d electrons that could cause a bonding interaction between the Ni and the Al atoms, strengthening the interactions between the Li and the H atoms, and 'freeing' the H atoms from the neighbouring [AlH(4)] groups as well.
我们使用第一性原理方法研究了 Ti 和 Ni 掺杂剂对 LiAlH(4)稳定性和键相互作用的影响。由于从总能量计算估计的占据能较低，Ti 和 Ni 都优先占据 LiAlH(4)的间隙位置。计算表明，掺杂剂显著降低了[AlH(4)]基团内 Al 和 H 原子之间的键相互作用，掺杂 LiAlH(4)体系中[AlH(4)]基团的稳定性和几何形状都发生了扭曲。然而，Ti 和 Ni 用不同的机制来改善 LiAlH(4)的脱氢性能。Ti 掺杂剂倾向于与其相邻的[AlH(4)]中的 Al 原子相互作用，从而将 H 原子从这些[AlH(4)]基团中“释放”出来。Ni 掺杂剂对 LiAlH(4)稳定性和键相互作用的影响归因于 Ni d 电子的诱导，这可能导致 Ni 和 Al 原子之间的键相互作用，增强 Li 和 H 原子之间的相互作用，并将 H 原子从相邻的[AlH(4)]基团中“释放”出来。
