Bonding between graphene and MoS2 monolayers without and with Li intercalation

Abstract

We performed density functional theory (DFT) calculations for a bi-layered heterostructure combining a graphene layer with a MoS2 layer with and without intercalated Li atoms. Our calculations demonstrate the importance of the van der Waals (vdW) interaction, which is crucial for forming stable bonding between the layers. Our DFT calculation correctly reproduces the linear dispersion, or Dirac cone, feature at the Fermi energy for the isolated graphene monolayer and the band gap for the MoS2 monolayer. For the combined graphene/MoS2 bi-layer, we observe interesting electronic structure and density of states (DOS) characteristics near the Fermi energy, showing both the gap like features of the MoS2 layer and in-gap states with linear dispersion contributed mostly by the graphene layer. Our calculated total DOS in this vdW heterostructure reveals that the graphene layer significantly contributes to pinning the Fermi energy at the center of the band gap of MoS2. We also find that intercalating Li ions in between the layers of the graphene/MoS2 heterostructure enhances the binding energy through orbital hybridizations between cations (Li adatoms) and anions (graphene and MoS2 monolayers). Moreover, we calculate the dielectric function of the Li intercalated graphene/MoS2 heterostructure, the imaginary component of which can be directly compared with experimental measurements of optical conductivity in order to validate our theoretical prediction. We observe sharp features in the imaginary component of the dielectric function, which shows the presence of a Drude peak in the optical conductivity, and therefore metallicity in the lithiated graphene/MoS2 heterostructure.

Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation

“…In addition, a recent theoretical work found that intercalated lithium ions enhances the binding energy through orbital hybridizations between cations (lithium ions) and anions (MoS 2 ) (ref. 32). Second, the intercalated lithium donates electrons to MoS 2 , which changes the oxidation states of Mo, and hence the electronic properties of MoS 2 (refs 33, 34).…”

Chemical Mass Production of MoS2/Graphene van der Waals Heterostructure as a High‐Performance Li‐ion Intercalation Host

“…It is obvious that MoS 2 /GR heterostructure exhibits markedly better electrochemical kinetic compared with MoS 2 /GR hybrid, well agreeing to the results of the CV measurement. The superior electrochemical kinetic of MoS 2 /GR heterostructure should be ascribed to the important role of MoS 2 /GR heterointerfaces in increasing the electronic conductivity of MoS 2 , enlarging the adsorption energy of Li‐ion on the surface of MoS 2 layer, and maintaining the high diffusion mobility of Li‐ion . Furthermore, the ultrasmall MoS 2 nanosheets can effectively shorten the Li‐ion transport path with more active sites for Li‐ion adsorption and reaction .…”

“…The superior electrochemical kinetic of MoS 2 /GR heterostructure should be ascribed to the important role of MoS 2 /GR heterointerfaces in increasing the electronic conductivity of MoS 2 , enlarging the adsorption energy of Li-ion on the surface of MoS 2 layer, and maintaining the high diffusion mobility of Li-ion. [26][27][28][29][30] Furthermore, the ultrasmall MoS 2 nanosheets can effectively shorten the Li-ion transport path with more active sites for Li-ion adsorption and reaction. [36] In addition, it is noteworthy that the MoS 2 /GR heterostructure delivers an enhanced specific capacity than MoS 2 /GR hybrid at the low current density, even higher than the theoretical value of pure MoS 2 (167 mAh g À 1 ).…”

“…In particular, the intimate face‐to‐face contact between MoS 2 and GR in MoS 2 /GR heterostructure can effectively endow MoS 2 with superior electron transport . Furthermore, several theoretical studies have revealed that the MoS 2 /GR atomic interface possesses an enhanced Li adsorption energy compared with MoS 2 sheets . The Li‐ions can diffuse faster between GR and MoS 2 layers with a lower diffusion barrier than that in MoS 2 interlayers .…”

“…[25] Furthermore, several theoretical studies have revealed that the MoS 2 /GR atomic interface possesses an enhanced Li adsorption energy compared with MoS 2 sheets. [26,27] The Li-ions can diffuse faster between GR and MoS 2 layers with a lower diffusion barrier than that in MoS 2 interlayers. [28][29][30] Moreover, MoS 2 /GR heterointerfaces can achieve a maximum intercalation at the ratio of 1 Li per Mo atom, [31] this means the interlayer-expanded MoS 2 resulting from the alternately stacked structure can possess an enhanced charge storage capability.…”