Darvish Ganji M, Hosseini-Khah S M, Amini-Tabar Z
Nanoscale Simulation Group, Nanotechnology Research Institute, Babol Noshirvani University of Technology, Babol, Iran.
Phys Chem Chem Phys. 2015 Jan 28;17(4):2504-11. doi: 10.1039/c4cp04399e. Epub 2014 Dec 10.
This work investigates hydrogen adsorption onto various graphene flakes such as coronene and coronene-like as suitable models of graphene within the framework of the DFT-B3LYP method. The non-local van der Waals (vdW) density functional (B3LYP-D3) method is used for both structural geometry optimization and total energy estimations. Calculations were carried out for a hydrogen molecule above a coronene surface with both conventional and vdW corrected DFT to investigate how these approaches perform in the case of hydrogen adsorption on a graphene surface. Our first-principles results within the B3LYP-D3/def2-TZVPP model show that hydrogen physisorbs on a coronene surface with an adsorption energy of -5.013 (kJ mol(-1)) which is in good agreement with the experimental value. The influence of the basis set and graphene flake size were also evaluated and the results indicate that these slightly affect the adsorption properties. We found also that it is crucial to use non-local dispersion interactions to get accurate results for hydrogen adsorption on a graphene surface. Furthermore, the co-adsorption of H2 molecules onto the graphene surface was investigated. The results obtained at the B3LYP-D3/def2-TZVP level show that H2 molecules can be physisorbed on both sides of the graphene layer with adsorption properties similar to those for a single surface. Finally, we showed that H2 molecules might be bound to the graphene surface via a bilayer adsorption scheme with weak adsorption energy. Charge population and electron density analysis confirm the weak binding nature of the system under consideration.
本工作在密度泛函理论（DFT）-B3LYP方法框架内，研究了氢在各种石墨烯片（如并五苯及类并五苯）上的吸附情况，这些可作为石墨烯的合适模型。非局域范德华（vdW）密度泛函（B3LYP-D3）方法用于结构几何优化和总能量估计。对并五苯表面上方的氢分子进行了常规DFT和vdW校正DFT计算，以研究这些方法在氢吸附于石墨烯表面的情况下的表现。我们在B3LYP-D3/def2-TZVPP模型下的第一性原理结果表明，氢以-5.013（kJ mol⁻¹）的吸附能物理吸附在并五苯表面，这与实验值吻合良好。还评估了基组和石墨烯片尺寸的影响，结果表明这些因素对吸附性能有轻微影响。我们还发现，使用非局域色散相互作用对于获得氢在石墨烯表面吸附的准确结果至关重要。此外，研究了H₂分子在石墨烯表面的共吸附。在B3LYP-D3/def2-TZVP水平获得的结果表明，H₂分子可以物理吸附在石墨烯层的两侧，吸附性能与单个表面的类似。最后，我们表明H₂分子可能通过双层吸附方案以较弱的吸附能与石墨烯表面结合。电荷布居和电子密度分析证实了所考虑体系的弱结合性质。
