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.