Enhanced Photocatalytic Ozonation Using Modified TiO2 With Designed Nucleophilic and Electrophilic Sites

Graphical The surface hydroxyl groups greatly promote O 3 adsorption due to the presence of nucleophilic O-sites and electrophilic H-sites. At the same time, the surface hydroxyl groups lead to the internal polarization of the surface-adsorbed O 3 and enhanced separation of photogenerated charge carriers, both of which are beneficial to promote O 3 activation and ROS formation. Therefore, TiO 2 −OH displays efficiently photocatalytic ozonation. Notably, TiO 2 −OH mineralization efficiency in pharmaceutical plant wastewater is as high as 97.6 % within 7 hours. Photocatalytic ozonation is considered to be a promising approach for the treatment of refractory organic pollutants, but the design of efficient catalyst remains a challenge. Surface modification provides a potential strategy to improve the activity of photocatalytic ozonation. In this work, density functional theory (DFT) calculations were first performed to check the interaction between O 3 and TiO 2 −OH (surface hydroxylated TiO 2 ) or TiO 2 −F (surface fluorinated TiO 2 ), and the results suggest that TiO 2 −OH displays better O 3 adsorption and activation than does TiO 2 −F, which is confirmed by experimental results. The surface hydroxyl groups greatly promote the O 3 activation, which is beneficial for the generation of reactive oxygen species (ROS). Importantly, TiO 2 −OH displays better performance towards pollutants (such as berberine hydrochloride) removal than does TiO 2 −F and most reported ozonation photocatalysts. The total organic carbon (TOC) removal efficiency reaches 84.4 % within two hours. This work highlights the effect of surface hydroxylation on photocatalytic ozonation and provides ideas for the design of efficient photocatalytic ozonation catalysts.