Disulfide Heterostructures Research Articles

One-pot synthesis of reduced graphene oxide/molybdenum disulfide heterostructures with intrinsic incommensurateness for enhanced lubricating properties

Inspired by the vision that incommensurately stacked multilayers can extend the already superior lubricating properties of two-dimensional (2D) nanomaterials, reduced graphene oxide/molybdenum disulfide (RGO/MoS2) heterostructures with different compositions are synthesized by a facile one-pot hydrothermal method for lubrication purpose. Two feed ratios for the graphene oxide and MoS2 precursors are designed to explore the relation among morphology, chemical composition and lubrication performances of the synthesized heterostructures. In the case of high loading amount of MoS2 on RGO, the novel structure of cocked MoS2 nanosheets provides extra steric hindrance effect to restrain the aggregate and settlement tendency when dispersed in paraffin oil. By comparing the tribological results, it is found that RGO/MoS2 heterostructures have better lubricating properties with lower coefficient of friction (0.09 in oil lubrication as additive and 0.02 in vacuum as coating) and higher wear resistance than single and physically mixed forms of RGO or MoS2. The proposed reason to this enhanced performance is the lower shear strength arising from the intrinsic lattice mismatch between RGO and MoS2.

Electron transfer and coupling in graphene-tungsten disulfide van der Waals heterostructures.

The newly discovered two-dimensional materials can be used to form atomically thin and sharp van der Waals heterostructures with nearly perfect interface qualities, which can transform the science and technology of semiconductor heterostructures. Owing to the weak van der Waals interlayer coupling, the electronic states of participating materials remain largely unchanged. Hence, emergent properties of these structures rely on two key elements: electron transfer across the interface and interlayer coupling. Here we show, using graphene-tungsten disulfide heterostructures as an example, evidence of ultrafast and highly efficient interlayer electron transfer and strong interlayer coupling and control. We find that photocarriers injected in tungsten disulfide transfer to graphene in 1 ps and with near-unity efficiency. We also demonstrate that optical properties of tungsten disulfide can be effectively tuned by carriers in graphene. These findings illustrate basic processes required for using van der Waals heterostructures in electronics and photonics.