Ultrasmooth Sliding Contact Interfaces Driven by Vanadium in WS2-V/MAC Gel Hybrid Systems toward Enhanced Vacuum Lubrication.

Contact interfaces fundamentally govern the friction behavior and wear mechanisms of tribological systems through their inherent physical and chemical characteristics. This work presents an interfacial engineering strategy that constructs an ultrasmooth and adaptive sliding contact interface by synergistically combining vanadium-doped tungsten disulfide (WS2-V) films with a multialkylated cyclopentanes (MACs) gel. We demonstrate that vanadium doping acts not merely as a microstructural modifier but as a crucial driver for creating a chemically active and mechanically robust interface. Optimal V doping (∼10 at. %) transforms the WS2 film from a porous, columnar architecture into a dense nanocomposite, while simultaneously introducing V-S species that enhance interfacial compatibility. This V-modified WS2 surface exhibits exceptional adsorption and retention of the MACs oil molecules and gelator. Under vacuum conditions, this dynamic interface exhibits self-smoothing capabilities, effectively healing surface asperities and maintaining an ultralow shear plane with an areal arithmetic mean roughness (Sa) as low as 2.0 nm. The optimal hybrid system (WS2-10%V/MACs gel) achieves a stable friction coefficient of 0.051 and reduces the wear rate to 1.1 × 10-8 mm3/(N·m). This work establishes a dopant-mediated paradigm for actively engineering solid-gel contact interfaces, providing a foundational design principle for next-generation lubrication in space mechanisms.