摘要
过渡金属元素Hf被设计成通过占据Co原子、Zr原子和间隙位点来添加到ZrCoH_(3)中.通过第一性原理计算研究了Hf对ZrCoH_(3)放氢的影响.发现用Hf掺杂会使ZrCoH_(3)不稳定,导致氢离解能(Ed)、Co-H平均单位键长的键序(SBOCo-H)降低,顺序为Zr_(16)Co_(16)H_(48)> Zr_(16)Co_(16)HfH_(48)> Zr_(16)Co_(15)HfH_(48)> Zr_(15)Co_(16)HfH_(48).理论研究表明在ZrCoH_(3)-Hf体系中,较弱的Co-H共价键相互作用、金属特性和Hf-H键的形成都有利于提高ZrCoH_(3)的放氢能力. Hf原子优先占据间隙位,但这对氢离解能影响很小,氢离解能与位置能之间存在悖论关系.尽管Zr_(15)Co_(16)HfH_(48)化合物具有低的氢离解能,表现出良好的放氢性能,但在实际应用Hf占据Zr位时需要消耗过高的能量成本.
The transition metal element Hf is designed to be added to ZrCoH_(3) by occupying Co atoms,Zr atoms and interstitial sites.The effect of Hf on the hydrogen evolution of ZrCoH_(3) are investigated by first-principles calculations.It is found that substitution with Hf destabilizes ZrCoH_(3),leading to a reductions in the dehydrogenation energy(Ed)and the Co-H average bond length with the order of Zr_(16)Co_(16)H_(48)>Zr_(16)Co_(16)HfH_(48)>Zr_(16)Co_(15)HfH_(48)>Zr_(15)Co_(16)HfH_(48).Theoretical studies show that in the ZrCoH_(3)-Hf system,the weaker Co-H covalent bond interaction,metallic properties and the formation of Hf-H bonds are all beneficial to improve the hydrogen release capacity of ZrCoH_(3).Hf atoms preferentially occupy interstitial sites,but this has little effect on the hydrogen dissociation energy.Although the Zr_(15)Co_(16)HfH_(48)compound has low hydrogen dissociation energy and exhibits good hydrogen desorption performance,it needs to consume too high energy cost when Hf occupies Zr site in practical application.
作者
曾祥
杨友山
ZENG Xiang;YANG You-Shan(School of Agriculture,Forestry Engineering and Planning,Tongren University,Tongren 554300,China)
出处
《原子与分子物理学报》
北大核心
2024年第4期180-188,共9页
Journal of Atomic and Molecular Physics
基金
贵州省教育厅青年项目(黔教技[2022]355号)。
关键词
储氢
ZrCoH_(3)
第一性原理计算
放氢性能
过渡金属元素掺杂
Hydrogen storage
ZrCoH_(3)
First-principles calculations
Dehydrogenation performance
Transition metal element doping
