Photodegradation of CH3I on mesoporous TiO2-B nanofibers with Au nanoparticles

Au nanoparticles deposited on mesoporous TiO2-B nanofibers have been prepared, characterized, and used to catalyze photoreactions of iodomethane. High-density gold-particle deposition on TiO2-B is obtained by electrostatic and/or chemical force between the particles of TiO2-B and Au capped with -SC(H)(CO2H)(CH2CO2H) through pH control. The capping groups on the gold particles can be removed after 400 °C calcination. It is found that the nature of the inorganic acids used for pH adjustment has effects on particle morphology and deposition. Two other methods, i.e., preparation of TiO2-B nanofibers in the presence of gold particles and preparation of gold nanoparticles in the presence of TiO2-B particles (deposition-precipitation method), are also investigated. However, the former method produces a low-density deposition and the latter one induces a morphology change of the TiO2-B and an increase of the Au in size. Fourier transform infrared spectroscopy has been employed to study and to compare the photoreactions of CH3I on TiO2-B and Au/TiO2-B and the effect of O2. The presence of gold particles on TiO2-B increases the efficiency of CH3I photodegradation, forming adsorbed methoxy and formate. The role of gold is also discussed.