Anatase/brookite TiO2–Bi2WO6 multiheterojunction photocatalyst (TabB) has been synthesized via solvothermal method and its physiochemical properties compared with anatase TiO2–Bi2WO6 (TaB) and brookite TiO2–Bi2WO6 (TbB) with single-heterojunction structure. Based on X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) analyses, a heterojunction was formed between TiO2 and Bi2WO6 crystals. All of the TaB, TbB, and TabB samples consisted of free plate-like Bi2WO6 particles covered by many TiO2 nanoparticles. Compared with pure TiO2 (anatase and brookite), the absorption band edge of TabB was red-shifted and the bandgap decreased. The photocatalytic activity of the as-prepared samples under visible-light irradiation was investigated using rhodamine B (RhB), revealing photocatalytic activity in the order TabB > TaB > TbB. The heterojunction structure played a vital role in enhancing charge carrier separation and thus enhancing the photocatalytic activity. The related mechanism of the heterojunction photocatalyst is systematically discussed.
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The authors acknowledge support from the National Public Research Senior Scholars and Visiting Scholars Project (no. 201706895007), National Natural Science Foundation of China (51472154), Shanghai Municipal Science and Technology Commission (16595800500), Shanghai Municipal Education Commission (Peak Discipline Construction Program), National Key Technology Research and Development Program of the Ministry of Science and Technology of China (no. 2014BAE12B02), and Yunnan Province Science and Technology Cooperation Project (2015IB009).