High Atomic Oxygen Erosion Resistance of Mos2-Based Films by Dynamic Redox Mechanism of Ceo2

Abstract

Low Earth orbit atomic oxygen (AO) exposure may induce irreversible degradation in spacecraft surface MoS₂-based films. Here, we demonstrate that doping rare earth compounds in molybdenum disulfide (MoS2)-based films can optimize the structure and properties of MoS2-based films. However, distinct modification effects exist among different rare earth compounds. The most interesting of these is our finding that doping with CeO2 not only optimizes the structure of MoS2 (a rare-earth element commonality), but also confers dynamic redox self-healing properties to the films, a mechanism derived from the synergistic effect between reversible Ce3+/Ce4+ conversion and oxygen vacancy dynamic equilibrium. These mechanisms enable both films to maintain ultra-low friction coefficients below 0.02 and frictional lifetimes exceeding 1×106 laps after AO irradiation.

Keywords: Key words: Rare earth doping, AO, Molybdenum disulfide-based films, Dynamic redox