Preparation of Red TiO with Excellent Visible Light Absorption from Industrial TiOSO Solution for Photocatalytic Degradation of Dyes.

At present, it is still difficult to significantly reduce the bandgap of TiO to promote its visible light absorption. Herein, we first synthesized sulfur-doped TiO from industrial TiOSO and then successfully synthesized red TiO nanoparticles by calcination with the N source melamine. Theoretical calculations show that predoped S could markedly decrease the formation energy and substitution energy of N-doped TiO, especially in high N/Ti ratios. The red TiO nanoparticles have a low bandgap (2.10 eV) and exhibit remarkable visible light absorption capacity. Electron paramagnetic resonance measurements show that the red TiO has abundant oxygen vacancies and Ti. The synergetic effect of Ti, oxygen vacancies, and nonmetallic element doping leads to the bandgap of TiO significantly being reduced. In addition, the red TiO exhibits great photocatalytic activity in the visible light degradation of rhodamine B (Rh.B) and methylene blue (MB). This study provides a new idea for the preparation of TiO with high visible light absorption.