Fluorine-regulated surface chemical state of titanium dioxide (TiO

Abstract

Environmental context As a new type of photocatalytic material, nano-titanium dioxide can be applied in the field of energy and environmental protection. This research uses ammonium bifluoride to modify the titanium dioxide and analyses it in combination with interface chemistry theory, and finds that its photocatalytic efficiency has been greatly improved. This provides new ideas for wastewater treatment and pollutant degradation. Abstract Titanium dioxide (TiO2) was prepared by hydrothermally adjusting titanium sulfate with ammonium hydrogen fluoride. The UV-visible absorption spectra show that there was no significant redshift in the absorption sideband of the sample, but the addition of ammonium hydrogen fluoride affected the morphology and microstructure of the sample. When the molar ratio of F to Ti was 1.5, the specific surface area of TiO2 more than doubled, the surface complexation mode changed significantly and the number of surface-active sites increased by a factor of 16.24. The photocatalytic degradation measurements show that the decolourisation rate of the photocatalyst prepared by fluorine control was increased by 40 % compared with the uncontrolled sample. The analysis of the combined state of the catalyst surface shows that the photocatalytic degradation efficiency and the amount of deprotonated TiO− as well as the number of positively charged oxidation states of methylene blue are clearly correlated. Furthermore, the number of active sites of the catalyst increased and the electrostatic interaction between fluorine and titanium formed a F-Ti dipole moment, which intensified the interaction between the negatively charged TiO− ion and the positively charged quinone methylene blue molecule. The lone pair electron of N in the quinone methylene blue molecule and the 3d orbital of Ti formed a metastable complex through coordination, and demethylation of the methylene blue molecules was completed.