Preparation of fine, uniform nitrogen- and sulfur-modified TiO₂ nanoparticles from titania nanotubes

TiO₂ nanoparticles modified with nitrogen and sulfur were prepared from titania nanotubes by a facile wet chemistry method. The samples synthesized with different thiourea/TiO₂ ratios showed a uniform nanoparticle size distribution centred at approximately 10 nm with a developed specific surface area of 246 m² g^-1. These modified nanosized photocatalysts exhibited higher photocatalytic activity for the degradation of gaseous isopropanol than unmodified titania nanotubes under visible illumination. This could be attributed to the synergistic effects of a large specific surface area, strong absorption in the visible region, a redshift in the adsorption edge, and surface adsorption modification induced by nitrogen and sulfur compounds.