Effect of plasma treatment on surface properties of TiO2 nanoparticulate films

TiO2 nanoparticle films were prepared by plasma-enhanced chemical vapor deposition, and subsequently, their surfaces were treated by TiCl4 and O2 plasmas, respectively. Experiments of phenol photodegradation show that the TiO2 film treated by O2 plasma presents much higher photocatalytic activity than that treated by TiCl4 plasma. X-ray photoelectron spectral analyses indicate that more active species, such as O2−, are formed on surface of the film treated by O2 plasma than that treated by TiCl4 plasma. The energy levels of the surface species and the photogenerated electronic transitions via these surface species are further investigated by surface photovoltage spectra (SPS) and electric field-induced surface photovoltage spectra (EFISPS).