Synthesis of Bi₂WO₆ hierarchical structures constructed by porous nanoplates and their associated photocatalytic properties under visible light irradiation

We report a facile template-free solvothermal approach for the synthesis of Bi₂WO₆ hierarchical structures assembled by porous nanoplates, the unique morphology of which endows the sample with high photocatalytic activity under visible light irradiation. The synthesized Bi ₂WO₆ hierarchical structures have diameters of ∼1 μm, and consist of multiple crossed-plates in three-dimensional configuration. A possible three-stage formation mechanism was proposed for the construction of hierarchical structures, and Ostwald ripening was responsible for the formation of meso-pores. The as-prepared Bi₂WO₆ hierarchical structures exhibited high photocatalytic activity on the degradation of Rhodamine B under visible light irradiation, due to the larger specific surface area (20.4 m² g^-1), unique hierarchical structures with multiple-crossed porous layer and higher crystallinity. A comparison of photocatalytic performance between the hierarchical structures and other samples with different morphologies was performed. The main active species of Bi₂WO₆ hierarchical structures during a photocatalytic process were determined to be O^2- and h⁺ radicals by dissolving different trapping agents.