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.