受最近关于penta-MgN8板材的报告的激励[Mater。今天Phys.2023,38,101259]这是首次实现5型五边形2D镶嵌,其中暴露了规则分布的Mg离子,我们进行了密度泛函理论研究H2分子与一维五纳米管的相互作用,2Dpenta-sheet,和基于penta-MgN8的3D多孔结构。我们发现,当penta-MgN8薄片组装成3D多孔结构或弯曲成纳米管时,带隙从1.18增加到1.35和1.88eV,并且得到的导数是动态稳定的。当引入H2分子时,纳米管在吸附方面表现最好,其中每个Mg离子可以吸附三个H2分子:两个在外表面上,一个在内表面上。与2D薄片和3D多孔结构的情况相比,纳米管的弯曲几何形状使外表面上的Mg离子更暴露。导致对H2的更强吸附。对于所研究的五片和五纳米管,重量容量(体积容量)为4.25wt%(63g/L)和4.25wt%(65g/L),在1个大气压下,相应的解吸温度为115和162K,分别,而对于3D多孔结构,由于有限的空间和较小的曲率,吸附性能较差,导致强烈的空间位阻和较少的镁离子暴露配置。此外,还讨论了温度和压力对吸附的影响。
Motivated by the recent report on penta-MgN8 sheet [Mater. Today Phys. 2023, 38, 101259] that is the first realization of type-5 pentagonal 2D tessellation with exposed regularly distributed Mg ions, we carried out density functional theory studies on the interactions of H2 molecules with 1D penta-
nanotube, 2D penta-sheet, and 3D porous structures based on penta-MgN8. We found that when the penta-MgN8 sheet is assembled to a 3D porous structure or curved to a
nanotube, the bandgap increases from 1.18 to 1.35 and 1.88 eV, and the resulting derivatives are stable dynamically. When H2 molecules are introduced, the
nanotube behaves best in adsorption, where each Mg ion can adsorb three H2 molecules: two on the outer surface and one on the inner surface. The curved geometry of the
nanotube makes the Mg ion on the outer surface more exposed as compared with the situations of the 2D sheet and 3D porous structure, resulting in stronger adsorptions to H2. The gravimetric capacity (volumetric capacity) is 4.25 wt % (63 g/L) and 4.25 wt % (65 g/L) for the studied penta-sheet and penta-
nanotube, and the corresponding desorption temperature is 115 and 162 K at 1 atm pressure, respectively, while for the 3D porous structure, the adsorption performance is poor due to the limited space and the less curvature, leading to strong steric hindrance and less exposed configuration for Mg ions. Moreover, the effects of temperature and pressure on adsorption are also discussed.