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 H 2 Ti 3 O 7 crystal in aqueous media, a colloidal aqueous suspension of titanate nanosheets doped with Rh atoms at the Ti sites (TiNS:Rh z , z = amount of Rh, [Ti 3−z Rh z O 7 ] 2− ) was prepared. Oxidative degradation of methylene blue (MB) by TiNS:Rh z 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:Rh z 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+ and Rh 4+ strongly contributes to the oxidative degradation of MB in the presence of TiNS:Rh z under UV light irradiation.