Effect of surface ethoxy groups on photoactivity of TiO2 nanocrystals

TiO2 nanocrystals modified by ethoxy groups were prepared by a facile nonhydrolytic solvothermal method and characterized by XRD, TEM, TG-DTA and XPS, which showed an enhanced visible-light photocatalytic activity on the degradation of Rhodamine B compared with TiO2 modified by benzyloxy groups and the “naked” TiO2. The adsorption and degradation pathway of Rhodamine B on TiO2 modified by ethoxy groups were also investigated. The zeta-potential (ζ) results showed that the TiO2 modified by ethoxy groups had high negative surface charge, which incited the positive -N(Et)2 group of RhB absorbing on the TiO2 surface and preferably led the N-dealkylation pathway under visible light irradiation.

The TiO2 nanocrystals modified by ethoxy groups had plenty of surface negative charges, which selectively absorbed the positive -N(Et)2 group of RhB and resulted in N-dealkylation process under visible-light irradiation.Highlights► High surface charge of ethoxy groups modified TiO2 nanocrystals promoted the adsorption of RhB on catalysts. ► Positive -N(Et)2 group of Rhodamine B absorbed selectively on the catalyst surface. ► RhB underwent the N-dealkylation process on ethoxide groups modified nanocrystals.