Different interactions of gaseous CH3I with both Ag nanoparticles and Ag+ ions included in mercaptopropyl functionalized silica gels

Mercaptopropyl functionalized silica gels were prepared and interacted with Ag0 nanoparticles and Ag+ ions. After that, these gels were all exposed to gaseous CH3I. To investigate the silver oxidation states and interactions with the surrounding gels, peak shifts were observed using X-ray photoelectron spectroscopy. The cleavage of mercaptopropyl during the electron-beam irradiation applied for Ag0 nanoparticle production was also discussed. The produced Ag nanoparticles formed covalent bonds with the mercaptopropyls. However, in this study, decomposition of the gaseous CH3I was not observed, and the CH3I remained on the surfaces of the Ag nanoparticles. On the other hand, Ag+ ions formed ionic bonds with the mercaptopropyls, and the physisorption of gaseous CH3I on the Ag+ ions occurred. Thereafter, the gaseous CH3I was decomposed by UV light, and the Ag+ ions and iodide interacted to form AgI. Different reactions of gaseous CH3I were observed depending on the oxidation states of the silver.