Photocatalytic oxidation of gas-phase Hg0 by Fe-doped TiO2 hollow microspheres

Fe-doped TiO2 hollow microspheres were prepared by the hydrothermal method and characterized by the X-ray diffraction (XRD), the Scanning Electronic Microscopy (SEM), the Energy Dispersive X-Ray (EDX), the Brunauer-Emmett-Teller (BET), and the UV–visible diffuse-reflectance spectrum (UV–Vis). The as-prepared samples were evaluated for photocatalytic removal of Hg0 under ultraviolet light irradiation. The results showed that the sample had a good photocatalytic performance. When M* (the molar ratio of Fe/Ti) was 0.05, the mercury removal efficiency reached up to 100%. It was found that the incorporation of iron narrowed the energy band gap of TiO2 (from 3.11 eV to 2.58 eV) and the absorbing boundary increased from 398 nm to 480 nm. While too much Fe3+ may occupy the capture sites of electrons and holes, which leads to a decrease of photocatalytic efficiency.