Photocatalyst TiO2 assisted preparation by phosphonium ionic liquids enhancing degradation rate of VOCs

Abstract

A series of TiO2 modified by phosphonium ionic liquids (PILs) and additives containing heteroatoms were synthesized. Among them, P, B, F and P, P, F doped catalysts effectively inhibited the crystal growth of TiO2, decreased the pore size and increased the surface area. What's more, PILs-TiO2 exhibited superior characteristics to those mentioned above. The characterization by FTIR, XPS and EPR demonstrated the generation of chemical bands and the introduction of oxygen vacancies and hydroxyl radicals in the samples. The photocatalytic degradation performance was evaluated and compared under simulated visible light for gaseous toluene. Compared with TiO2, degradation rate increased from 10.28 % to 28.42 %, 41.70 % and 46.23 % for [P4443][Br], [P4443][PF6] and [P4443][BF4] modified TiO2, respectively. In addition, the best photocatalytic degradation rate for T-P/Br, T-P/P/F and T-P/B/F increased to 13.54 %, 42.92 % and 43.78 %, respectively. Synergistic effect of elements in PILs resulted in beneficial photocatalytic degradation, which varied depending on the combination of different elements. Both heteroatoms in PILs and structure of PILs have significant effects on photocatalytic performance. The simulation showed that the presence of compactness of hydrogen bond network formed by PILs was beneficial, which was affected by the number of hydrogen bonds and the anion size.