Superhydrophobic MoS2 Nanosheet–Cu2O Nanoparticle Antiwear Coatings

The superhydrophobic MoS2 nanosheet–Cu2O nanoparticle antiwear coatings were constructed by immersing the sputtered MoS2 coatings to a solution of CuSO4 and sodium citrate. The contact angle (CA) and sliding angle (SA) of the coatings were ∼164 and 2°, respectively. MoS2 nanosheets wrapped with Cu2O layers were ∼54 nm thick. On the nanosheets, the Cu2O nanospheres were ∼60 nm in size, and numerous Cu2O nanospheres aggregated into Cu2O clusters with 1–5 μm length. The cooperation of microstructures (Cu2O clusters) and nanostructures (Cu2O nanoparticles) and the arrangement of the Cu2O clusters on the surface of the sputtered MoS2 coatings resulted in the superhydrophobic property of the MoS2 nanosheet–Cu2O nanoparticle coating. Besides, the MoS2 nanosheet–Cu2O nanoparticle coating showed outstanding stability and durability (almost 1 year) with superhydrophobic and tribological properties, including a relatively low friction coefficient (as low as 0.008–0.015) and a long antiwear life (∼1.0 × 106 r). During friction, Cu2O nanospheres can roll at the friction interface, show “nanobearing effects”, and then reduce the friction coefficient of the coatings.