Synthesis of mesoporous BiOBr 3D microspheres and their photodecomposition for toluene

Abstract

In this article, a facile solvothermal method was introduced to synthesize mesoporous BiOBr microspheres with Bi(NO(3))(3) as Bi source. The synthesized catalysts were characterized by XRD, SEM, TEM, XPS, UV-vis, TG-DTA, and N(2)-adsorption-desorption, and their photoactivity was evaluated by gaseous toluene both under UV and UV-vis irradiation with Degussa TiO(2) P(25) as reference. The prepared BiOBr catalysts were of pure tetragonal phase and its band gap energy was calculated to be about 2.64eV. Comparing with P(25), BiOBr showed promoted photocatalytic activity under UV-vis irradiation, during which more than 90% of toluene was eliminated after 5h irradiation. Kinetic analysis further demonstrated the enhanced activity of BiOBr under UV-vis irradiation and the reaction rate constant k of BiOBr was nearly 2 times higher than that of P(25). The superior activity of BiOBr under UV-vis irradiation can be attributed to its hierarchical structure and suitable band gap energy. Moreover, the reacted intermediates under different light source were identified by GC-MS. Fifteen main intermediates were identified and a tentative pathway of toluene degradation by BiOBr was proposed.