Molybdenum disulfide (MoS₂) is widely utilized as a lubricant in aerospace, machinery, and electronics due to its unique layered structure and interlayer slip characteristics. Understanding the tribological behaviors of MoS₂-based films under varying atmospheric conditions, including oxidizing and specialized atmospheres, is crucial for developing environmentally adaptive lubricants. Here, we fabricated pure MoS₂ and Ag-doped MoS₂/Ag composite films via magnetron sputtering, focusing on their tribological performance in argon, CO₂ and O₂ atmospheres. Our results demonstrate that the friction coefficients of both films in argon and CO₂ are comparable to those in vacuum, with these environments promoting the formation of a continuous tribofilm on the counterpart ball surface, thereby reducing wear rates. Remarkably, in an oxygen environment, the MoS₂/Ag composite film exhibits a ~50% reduction in the friction coefficient (0.027) and a threefold decrease in wear rate compared to vacuum conditions. This exceptional performance is attributed to the friction-induced metal oxide nanoparticles coated with Ag, forming a “brick-mud” structure that slides with MoS₂ (002) nanosheets to achieve low friction and wear. Furthermore, the addition of Ag enhances the film’s ability to repair sliding interfaces, mitigating abrasive wear. Our study elucidates the mechanisms driving the low-friction behavior of MoS₂-based films in atmospheric environments, offering valuable insights for the development of high-performance lubricants for extreme conditions.

Because of profound applications of two-dimensional molybdenum disulfide (MoS₂) and its heterostructures in electronics, its thermal stability has been spurred substantial interest. We employ a precision muffle furnace at a series of increasing temperatures up to 340 °C to study the oxidation behavior of continuous MoS₂ films by either directly growing mono- and few-layer MoS₂ on SiO₂/Si substrate, or by mechanically transferring monolayer MoS₂ or hexagonal boron nitride (h-BN) onto monolayer MoS₂ substrate. Results show that monolayer MoS₂ can withstand high temperature at 340 °C with less oxidation while the few-layer MoS₂ films are completely oxidized just at 280 °C, resulting from the growth-induced tensile strain in few-layer MoS₂. When the tensile strain of films is released by transfer method, the stacked few-layer MoS₂ films exhibit superior thermal stability and typical layer-by-layer oxidation behavior at similarly high temperature. Counterintuitively, for the MoS₂/h-BN heterostructure, the h-BN film itself stacked on top is not damaged and forms many bubbles at 340 °C, whereas the underlying monolayer MoS₂ film is oxidized completely. By comprehensively using various experimental characterization and molecular dynamics calculations, such anomalous oxidation behavior of MoS₂/h-BN heterostructure is mainly due to the increased tensile strain in MoS₂ film at elevated temperature.