Phosphonium ionic liquid-promoted Ce-doped nitrogen-rich TiO2 for degradation gaseous pollutant under visible light irradiation

Abstract

Altering physicochemical properties of TiO2 based on modifying the cation and anion structure of ionic liquids (ILs) is of great interests for environment. Up to date, the research involving IL-assisted synthesis of TiO2 was focused on imidazolium IL, and much less attention was devoted to IL with other structures. Hence, strategy for preparation of TiO2 in phosphonium IL is presented to control the growth of TiO2 nanocrystals. The as-prepared noble cerium-doped nitrogen-rich phosphonium IL-TiO2 photocatalyst with assisted by tributyl(propyl)phosphonium tetrafluoroborate exhibits a higher specific surface area and smaller crystallite size, which is conducive to the production of more and faster active substance, such as hydroxyl oxygen. When evaluated for photocatalysis of gaseous toluene under visible light irradiation, the sample manifests high degradation rate and efficiency, as well as excellent recycling performance due to the existence of superoxide radical produced by the Ce3+/Ce4+ redox reaction. The introduction of phosphonium IL and Ce greatly enhanced charge separation efficiency and promoted production of active substances. Nitrogen also existed in the form of interstitial nitrogen and substituted nitrogen improves its response to visible light. This work shows promising application of phosphonium IL for highly enhanced TiO2 photocatalytic performance.