Bifunctional Mn²⁺ grafted Ultra-small TiO₂ nanoparticles on carbon cloth with efficient toluene degradation in a continuous flow reactor

Vacuum ultraviolet (VUV) light-induced photocatalytic degradation of volatile organic compounds (VOCs) is a promising strategy to solve many air pollution problems. However, the effectiveness of the process depends on the photocatalyst adopted. In this study, ultra-small TiO₂ (USTiO₂) nanoparticles were first synthesized through an acid-assisted solvent method; then, Mn²⁺ was added to form a Mn²⁺/USTiO₂ composite, which was then deposited onto a carbon cloth substrate by a facile dropping-drying process. Photo-generated carrier separation of Mn²⁺/USTiO₂ was enhanced and electron recombination was suppressed ascribed to the Mn²⁺ grafting. Residual O₃ produced by the VUV light was also thoroughly decomposed via the Mn valence state shift, forming reactive oxygen species to further enhance toluene degradation activity. Under VUV light illumination, the optimized 2.0% Mn²⁺/USTiO₂ on carbon cloth showed a superior toluene degradation efficiency of 98%, with high mineralization efficiency up to 50%. This hybrid structure exhibited robust stability of over 400 min.