Effects of vacuum on photocatalytic activity of TiO2

Contamination outgassed from spacecraft's materials can degrade optical devices in orbit. Therefore, solving the contamination problem is important because it in uences the success of spacecraft missions. In this study, methyl red (MR) and oleamide were decomposed in vacuum by TiO 2 photocatalyst. Absorbance spectra, mass decrease and GC/MS were measured after and before decomposition. In vacuum, TiO 2 could decompose MR to intermediate products, whereas it could not decompose the intermediate products to volatile substances because TiO 2 cannot open benzene rings of the intermediate products. On the other hand, TiO 2 could decompose oleamide to volatile substances even in vacuum. However, decomposition by TiO 2 stopped after a certain period of time in vacuum. The decrease in mass for oleamide by photocatalytic reaction in vacuum was enough compared to standard molecular contamination levels.