An analysis on optical degradation of ZnO/silicone white paint under proton exposure

The optical degradation mechanism of ZnO/silicone white paint caused by 50 keV protons was investigated in terms of X-ray photoelectron spectroscopy (XPS). The results show that the change in solar absorptance Δαs increases with increasing proton fluence, and the variation of Δαs has a good relationship with the formation of the oxygen vacancies in ZnO and the Si–CO functional groups in silicone binder. With increasing the proton fluence, both the area ratio of lattice oxygen peak to XPS O1s spectrum and the peak area in Zn3d spectra decrease, indicating that the percentage of lattice oxygen decreases and the amount of oxygen vacancies increases. Meanwhile, the area ratio of the Si–CO peak to XPS Si2p spectrum increases, demonstrating the formation of Si–CO chromophores in silicone binder. Both the oxygen vacancies and the Si–CO chromophores can lead to an optical degradation of ZnO/silicone white paint under proton exposure.