论文部分内容阅读
采用基于密度泛函理论的赝势平面波第一性原理方法,研究了LiNH2缺陷及其掺杂原子交互作用对其释氢影响.通过对其进行优化求得它们的局域最稳定结构并计算了含间隙H原子缺陷的LiNH2及其掺杂合金的结合能、间隙缺陷形成能、态密度和电荷布居.结果表明:系统结合能不能反映LiNH2及其掺杂合金的释氢性质;平衡时,LiNH2中有一定的间隙氢原子存在,Mg,Ti掺杂使形成能大大降低,大大增大了间隙氢的浓度.间隙H原子在带隙引入了缺陷能级使带隙大大减小,提高释氢能力.间隙H原子导致[NH2]-中N—H原子间相互作用减弱,容易释氢.间隙H与[NH2]-中N存在共价作用,可以解释LiNH2释氢反应中NH3的放出.当存在掺杂时,N—H键的键强不均衡,部分较弱,部分较强,较弱的N—H键中H容易放出.
The first-principle method of pseudopotential plane wave based on density functional theory was used to study the effect of LiNH2 defect and its interaction of doping atoms on hydrogen evolution. The most stable local structure of LiNH2 was calculated and calculated The binding energies, interstitial defect formation energies, density of states and charge population of LiNH2 with interstitial H atom defects and its doped alloys show that the system binding can not reflect the hydrogen releasing properties of LiNH2 and its doped alloys. At equilibrium, LiNH2 interstitial hydrogen atoms exist, Mg, Ti doping so that the formation can be greatly reduced, greatly increasing the concentration of interstitial hydrogen gap H atoms in the bandgap introduced a defect level to significantly reduce the band gap to improve the release Hydrogen capacity.The interstitial H atom leads to the weakening of the interaction between [NH2] - N-H atoms, which makes it easy to release hydrogen.The gap H is covalently linked with [NH2] - N, which can explain the release of NH3 in the hydrogen releasing reaction of LiNH2. When there is doping, the bond strength of N-H bond is not balanced, the part is weaker, the stronger the part is, and the weaker H-bond of N-H is easy to release.