Engineering a staggered type-II Bi₂WO₆/WO₃ heterojunction with improved photocatalytic activity in wastewater...

In recent years, the removal organic pollutants from wastewater by advanced oxidation processes, especially photocatalysis, has become a meaningful approach due to its eco-friendliness and low cost. Herein, staggered type-II Bi₂WO₆/WO₃ heterojunction photocatalysts were prepared by a facile hydrothermal route and investigated by modern physicochemical methods (X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption-desorption, and diffuse reflectance spectroscopy). The optimized BWOW-5 photocatalyst exhibited a H₂O₂-assisted photocatalytic methylene blue removal efficiency of 94.1% (k = 0.01414 min^-1) within 180 min under optimal reaction conditions, which is much higher than that of unmodified Bi₂WO₆ and WO₃ due to efficient separation of the photogenerated charge carriers. The trapping experiments demonstrated that photogenerated hydroxyl radicals and holes play a key role in the photodegradation reaction. Moreover, the optimized BWOW-5 heterojunction photocatalyst exhibited excellent activity in the H₂O₂-assisted degradation of other pollutants, namely phenol, isoniazid, levofloxacin, and dibenzothiophene with the removal rate of 63.1, 73.6, 95.0, and 72.4%, respectively. This investigation offers a design strategy for Bi₂WO₆-based multifunctional photocatalytic composites with improved activity for organic pollutant degradation.