Effects of Rh-doping on the photooxidative degradation activity of titanate nanosheets

To investigate the Rh-doping effect on the photooxidative degradation activity of titanate nanosheets prepared by exfoliation of an H2Ti3O7 crystal in aqueous media, a colloidal aqueous suspension of titanate nanosheets doped with Rh atoms at the Ti sites (TiNS:Rhz, z = amount of Rh, [Ti3-z RhzO7](2-)) was prepared. Oxidative degradation of methylene blue (MB) by TiNS:Rhz in aqueous media under UV light irradiation was studied. Using X-ray diffraction, diffuse reflection spectroscopy, and photoelectrochemical measurements, the electronic band structure of TiNS:Rhz was elucidated and was shown not to change with the amount of Rh doping at the Ti sites. However, the degradation of MB increased with an increase in Rh doping. From these results, it is suggested that the redox reaction between Rh-3 broken vertical bar and Rh-4 broken vertical bar strongly contributes to the oxidative degradation of MB in the presence of TiNS: Rhz under UV light irradiation.