Contrarian Design of Versatile MoS-Based Self-Lubrication Film.

Molybdenum disulfide (MoS) exhibits excellent lubrication capacity rooted in its layered structure, but it suffers significant structural and functional deterioration due to oxidation in ambient environments, limiting its applications. Concerted efforts are focused on enhancing the antioxidation ability of MoS, but challenges remain. This work conceptualizes and demonstrates a contrarian design of MoS-based film via metal incorporation and oxidation based on consideration of key fundamental principles of thermodynamics, chemistry, and physical mechanics. A three-pronged process finds a metal of negative mixing enthalpy with Mo to induce amorphization of film, leading to structural densification and suppression of abrasive metal oxides that are harmful to lubrication, promotes, rather than impedes, oxidation in a top layer to enhance wear resistance and allow friction activated lamellar structure, and seeks low stacking fault energy for easy sliding in the lamellar structure to ensure superb low-shear lubrication. A screening of selected transition metals identifies niobium (Nb) as the promising choice; ensuing experiments synthesize amorphous MoS-Nb (a-MoS-Nb) film with superior tribological benchmarks. The present design strategy regulates the morphology and composition of the film to achieve the concurrent low-friction and low-wear functionality, opening a fresh path to making versatile lamellar structured lubricants for wide use in diverse environments.