Optically Active Oxygen Defects in Titanium Dioxide Doped with Inorganic Acid Ions.

Doping inorganic acid ions represents a promising pathway to improving the photocatalytic activity of TiO, and oxygen vacancy has been regarded as the determinant factor for photocatalytic activity. A series of samples doped with Cl, NO, and SO was prepared via a simple sol-gel method. Two different oxygen vacancies in the crystal layer of NO/TiO and Cl/TiO were found, and those are [Ti]-V-[Ti] and [Ti]-Cl, respectively. The photocurrent of NO/TiO with [Ti]-V-[Ti] is significantly greater than that of Cl/TiO with [Ti]-Cl. The least oxygen vacancy is in the gel layer of SO/TiO, and the negligible photocurrent is due to difficulty in forming a stable sol. Furthermore, the process conditions for the application of TiO were investigated in this work. The optimal process parameters are to adjust the solution to pH = 3 during sol-gel preparation, to adopt 550 °C as the calcination temperature, and to use an alkaline electrolyte, while the rest of the preparation conditions remain unchanged. This work reveals a new avenue for designing efficient photocatalysts for air pollutant degradation.