论文标题
压缩应变对石墨烯氢存储能力的影响：密度功能理论研究
Influence of compressive strain on the hydrogen storage capabilities of graphene: A density functional theory study
论文作者
论文摘要
原始石墨烯不适合在环境条件下储存氢，因为它仅通过范德华相互作用结合氢分子。但是，可以通过在石墨烯单层上的掺杂或装饰金属原子来改善氢分子的吸附能。由于氢气吸附和金属原子的聚类问题，掺杂和装饰过程具有挑战性。为了改善原始石墨烯中的氢吸附能，我们已经探索了在抗压株存在下石墨烯单层的氢储存能力。我们发现，在双轴压缩应变的6％，4*4*1的石墨烯可以吸附10 h $ _2 $分子在石墨烯表面上方。发现此配置的H $ _2 $的平均结合能为-0.42 EV/H $ _2 $，非常适合可逆氢吸附。我们提出，4*4*1的石墨烯超级细胞可以吸附20 h $ _2 $分子的总数，导致高氢摄取9.4％。通过绘制状态的部分密度和表面电荷密度图，已经研究了碳和氢原子轨道之间的相互作用。石墨烯C-C键周围的电子密度在压缩应变的存在下增加，因此氢分子被强烈吸附。
Pristine graphene is not suitable for hydrogen storage at ambient conditions since it binds the hydrogen molecules only by van der Waals interactions. However, the adsorption energy of the hydrogen molecules can be improved by doping or decorating metal atoms on the graphene monolayer. The doping and decoration processes are challenging due to the oxygen interference in hydrogen adsorption and the clustering issue of metal atoms. To improve the hydrogen adsorption energy in pristine graphene, we have explored the hydrogen storage capabilities of graphene monolayer in the presence of compressive strain. We found that at 6 % of biaxial compressive strain, a 4*4*1 supercell of graphene can adsorb 10 H$_2$ molecules above the graphene surface. The average binding energy of H$_2$ for this configuration is found to be -0.42 eV/H$_2$, which is very suitable for reversible hydrogen adsorption. We propose that a 4*4*1 supercell of graphene can adsorb a total number of 20 H$_2$ molecules leading to a high hydrogen uptake of 9.4 %. The interaction between orbitals of carbon and hydrogen atoms and the charge transfer process have been studied by plotting the partial density of states and surface charge density plots. The electronic density around the C-C bonds of graphene increases in the presence of compressive strain, due to which hydrogen molecules are strongly adsorbed.
