Caturello Naidel A M S, F R V Silveira Julian, Da Silva Juarez L F
São Carlos Institute of Chemistry, University of São Paulo, PO Box 780, 13560-970, São Carlos, São Paulo, Brazil.
Phys Chem Chem Phys. 2020 Dec 7;22(46):26865-26875. doi: 10.1039/d0cp04573j.
An atomistic understanding of transition-metal dichalcogenide (TMD) nanoflakes supported on graphene (Gr) plays an important role in the tuning of the physicochemical properties of two-dimensional (2D) materials; however, our current atom-level understanding of 2D-TMD nanoflakes on Gr is far from satisfactory. Thus, we report a density functional theory investigation into the stabilization and binding mechanisms of (MoS2)n/Gr, where n = 1, 4, 6, 9, 12 and 16. We found an evolution of the (MoS2)n…Gr interactions from covalent and hybridization contributions for smaller nanoflakes (n = 1, 4) to vdW interactions for larger (MoS2)n nanoflakes (n ≥ 6); however, the coupling of the (MoS2)n and Gr electronic states for n = 1 and 4 is not intense enough to change the Dirac cones at the Gr monolayer. On average, the 1T'- and 2H-(MoS2)n nanoflakes bind with similar adsorption/interaction energies with Gr, and hence the (MoS2)n…Gr interactions do not change the high energetic preference of the 1T'- structures, which can be explained by the stabilizing role of the S-terminated edges in the 1T'-(MoS2)n in contrast with the destabilizing role of the edges in the 2H-(MoS2)n nanoflakes.
对负载在石墨烯（Gr）上的过渡金属二硫属化物（TMD）纳米片的原子层面理解，在二维（2D）材料的物理化学性质调控中起着重要作用；然而，我们目前对Gr上二维TMD纳米片的原子级理解还远不能令人满意。因此，我们报告了一项关于（MoS2）n/Gr（其中n = 1、4、6、9、12和16）的稳定性和结合机制的密度泛函理论研究。我们发现，（MoS2）n…Gr相互作用从小尺寸纳米片（n = 1、4）的共价和杂化贡献演变为大尺寸（MoS2）n纳米片（n≥6）的范德华相互作用；然而，n = 1和4时（MoS2）n与Gr电子态的耦合强度不足以改变Gr单层的狄拉克锥。平均而言，1T'-和2H-（MoS2）n纳米片与Gr的吸附/相互作用能相似，因此（MoS2）n…Gr相互作用不会改变1T'-结构的高能偏好，这可以通过1T'-（MoS2）n中S端边缘的稳定作用与2H-（MoS2）n纳米片中边缘的不稳定作用来解释。
