Synthesis of (S, N)-Codoped TiO2 Nanotubes with High Photocatalytic Activity

(S, N)-codoped TiO2 nanotubes were hydrothermally fabricated by treating solvothermally synthesized (S, N)- codoped TiO2 nanoparticles in a NaOH aqueous solution. As-fabricated nanotubes were amorphous but transformed to crystalline anatase after solvothermal treatment in an isooctane solution containing thiourea. X-ray diffraction, transmission electron microscopy, and ultraviolet-visible spectrophotometry were used to characterize the codoped TiO2 nanotubes and nanoparticles. The content of nitrogen and sulphur reached 13.9% and 39.7% in the codoped TiO2 nanoparticles, respectively, and were 13.7% and 40.5% in the nanotubes, respectively. Thus, the band gaps of the nanoparticles and nanotubes were narrowed with respect to pure TiO2 and indirect band gaps were introduced and so the light absorption edges were respectively extended to regions of visible light and infrared light. The crystalline nanotubes showed great photodegradation efficiency to methyl orange. The present article discusses some important patents related to TiO2 photocatalysts.