论文部分内容阅读
本文使用密度泛函理论(density functional theory,DFT)中的广义梯度近似(generalized gradient approximation,GGA)研究了经碱金属原子Li、过渡金属原子Ti和Fe原子修饰的富勒烯C18B2M(M=Li,Ti,Fe)的储氢性能.研究发现,C18B2由于B的替代掺杂,比C20对金属原子具有更高的结合能.由平均吸附能分析可知:C18B2Li对H2的吸附能力较弱,C18B2Fe对H2的吸附能力过强,而C18B2Ti对H2的平均吸附能介于0.45—0.59 e V之间,介于物理吸附和化学吸附之间(0.2—0.6 e V),因此可以实现常温下的可逆储氢.C18B2M(M=Li,Ti,Fe)能够吸附的H2数目最多分别为4,6和4.由储氢机理分析可知:C18B2Li主要通过碱金属离子激发的静电场来吸附H2,而C18B2Ti和C18B2Fe主要通过金属原子与H2之间的Kubas作用来吸附H2.由于C18B2Ti既有较大的储氢数目,又可以实现可逆储氢,因此有望开发成新型纳米储氢材料.
In this dissertation, fullerene C18B2M modified by alkali metal atom Li and Ti and Fe atoms of transition metal (M = Li , Ti, Fe) .It is found that C18B2 has higher binding energy than metal atom due to C substitution by B. The average adsorption energy shows that the adsorption capacity of C18B2Li to H2 is weak, while C18B2Fe H2 adsorption capacity is too strong, and C18B2Ti H2 average adsorption energy between 0.45-0.59 e V, between the physical adsorption and chemisorption (0.2-0.6 e V), it can be achieved at room temperature, the reversible Hydrogen storage.C18B2M (M = Li, Ti, Fe) can adsorb most of the number of H2, respectively, 4,6 and 4. By the hydrogen storage mechanism analysis shows: C18B2Li mainly by alkali ions excited electrostatic field to adsorb H2, and C18B2Ti And C18B2Fe mainly adsorb H2 through the Kubas interaction between the metal atom and H2. Due to the large hydrogen storage number and reversible hydrogen storage, C18B2Ti is expected to be developed into a new type of nano-hydrogen storage material.