Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (12): 2085-2093.DOI: 10.1016/S1872-2067(17)62952-8

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Highly photoreactive TiO2 hollow microspheres with super thermal stability for acetone oxidation

Li Lianga,b, Kaining Lia, Kangle Lva, Wingkei Hob, Youyu Duana   

  1. a Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, Hubei Province, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074, Hubei, China;
    b Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, N. T., Hong Kong, China
  • Received:2017-10-11 Revised:2017-10-30 Online:2017-12-18 Published:2017-12-29
  • Supported by:

    This work is supported by the National Natural Science Foundation of China (51672312, 21373275), the Science and Technology Program of Wuhan, China (2016010101010018, 2015070504020220), and the Dean's Research Fund-04257 from the Education University of Hong Kong.

Abstract:

TiO2 hollow microspheres (TiO2-HMSs) have attracted much attention because of their high photoreactivity, low density, and good permeability. However, anatase TiO2-HMSs have poor thermal stability. In this study, surface-fluorinated TiO2-HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2-NH4HF-H2O2 solution at 180℃. The effect of the calcination temperature on the structure and photoreactivity of the TiO2-HMSs was systematically investigated, which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation. We found that after calcination at 300℃, the photoreactivity of the TiO2-HMSs decreases from 1.39×10-3 min-1 (TiO2-HMS precursor) to 0.82×10-3 min-1 because of removal of surface-adsorbed fluoride ions. With increasing calcination temperature from 300 to 900℃, the building blocks of the TiO2-HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles, and the photoreactivity of the TiO2-HMSs steady increases from 0.82×10-3 to 2.09×10-3 min-1 because of enhanced crystallization. Further increasing the calcination temperature to 1000 and 1100℃ results in a decrease of the photoreactivity, which is ascribed to a sharp decrease of the Brunau-er-Emmett-Teller surface area and the beginning of the anatase-rutile phase transformation at 1100℃. The effect of surface-adsorbed fluoride ions on the thermal stability of the TiO2-HMSs is also discussed.

Key words: TiO2 hollow microsphere, Photocatalytic oxidation, Acetone, Fluorine, Thermal stability