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采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,分别计算纯净以及掺杂Ti的NaAlH4和Na3AlH6的晶格结构参数、能量变化和电子态密度(DOS),分析比较Ti掺杂对NaAlH4和Na3AlH6储氢性能的影响。结果表明:Ti掺杂后的晶格结构比原纯净的NaAlH4和Na3AlH6稳定,且脱氢所需能量减少。Ti替代Na后,Ti吸引周围的H原子,使Al-H键变弱;Ti替代Al,Ti-H键比原Al-H键明显减弱,使掺杂后脱氢所需能量降低。通过对比分析Ti掺杂对NaAlH4和Na3AlH6结构和态密度的影响,得出Ti的催化作用主要发生在脱氢反应的第一步。
The crystal structure parameters, energy changes and electronic density of states (DOS) of pure and doped Ti-doped NaAlH4 and Na3AlH6 were calculated respectively by the plane wave pseudopotential (PW-PP) method based on density functional theory (DFT) Effect of Doping on Hydrogen Storage Properties of NaAlH4 and Na3AlH6. The results show that the lattice structure after Ti doping is more stable than the pure NaAlH4 and Na3AlH6, and the energy required for dehydrogenation is reduced. When Ti is substituted for Na, Ti attracts surrounding H atoms and weakens the Al-H bond. Ti replaces Al and the Ti-H bond is significantly weaker than the original Al-H bond, reducing the energy required for post-doping dehydrogenation. By comparing and analyzing the effect of Ti doping on the structure and density of states of NaAlH4 and Na3AlH6, the catalytic effect of Ti mainly occurs in the first step of dehydrogenation reaction.