First-principles insights into atomic oxygen protection coatings composed of scale-like layered double hydroxide nanosheets

With human activities in outer space becoming increasingly frequent, including the construction of space stations and satellite constellations such as Starlink, OneWeb, and G60 Qianfan Constellation, the protection of spacecraft against atomic oxygen (AO) in the low-Earth orbit (LEO) has become critical. AO, characterized by its strong oxidative capability and high collisional energy, has been considered the most serious hazard to the LEO spacecraft. Recently, it was found that scale-like Mg-Al layered double hydroxide (LDH) coatings are highly effective in protecting flexible spacecraft parts from AO erosion. However, the AO protection mechanism of the scale-like coatings remains unclear, which limited the further development of this AO protection technology. The erosion process of AO takes place at the atomic scale and on the femtosecond time scale, making it difficult to reveal the microscopic mechanism solely by experimental and characterization studies. To address this, we investigated the interactions between AO and the coating materials using first-principles based calculations and simulations. By simulating the AO impact and calculating the AO adsorption energy on polysiloxane and LDH nanosheets, a possible AO protection mechanism was proposed using experimental and characterization studies. With the special scale-like structure, the coating mainly inhibits the AO erosion through the barrier effect on the coating surface and the obstruction effect inside coatings with long erosion paths. This work shows that the non-dense micro-nanostructure holds potential for AO protection, which will guide and expand the application of assembled nanomaterials in space exploration.