Photocatalytic degradation of Diuron in water – Impact of Rh impregnation on P25 visible light activity

Significant efforts have lately been dedicated to the development of visible light activated photocatalysts for the degradation of emerging pollutants in water. This study shows the impact of Rh addition on the photocatalytic performance of TiO 2 in Diuron degradation through various experimental approaches and modelling. Three samples with different Rh loading (0.5 %, 1 %, and 2 %) were synthesized, characterized, and their activities were evaluated. It was observed that the activity of RhP25 improved under white light irradiation with increasing Rh content. At low Rh loadings the Rh atoms interact with Ti and may be stabilized in the TiO 2 lattice. At higher loadings Rh interacts with the O atoms forming two different clusters Rh 3 O 4 and Rh 4 O 6 on the TiO 2 surface. This phenomenon was evidenced by DFT, XPS and XRD results. The addition of Rh induce new electronic states in the TiO 2 enhancing the visible light absorption. Photocatalytic experiments revealed a threefold increase in Diuron removal under white light irradiation for 2%RhP25 compared to P25, achieving 23 % degradation in comparison with the 7 % observed for the P25 without the Rh addition. Furthermore, repeated experiments did not show significant deterioration of the activity.