Solvothermal synthesis of orthorhombic Sb2WO6 hierarchical structures and their visible-light-driven photocatalytic activity.

We report the solvothermal synthesis of hierarchical structures of orthorhombic Sb2WO6 and their implementation as a visible-light-driven photocatalyst for the degradation of Rhodamine B. The obtained hierarchical structures constructed by tiny nanosheets are doughnut-like flat ellipsoids with concaves in the centres, and with typical sizes of 1.3 μm in length, 800 nm in width and 400 nm in thickness. The concave characteristics and sizes of Sb2WO6 hierarchical structures can be tuned by adjusting the volume ratio of EG-H2O. Time-dependent experiments reveal that the formation process of concave structures involves the aggregation of nanoparticles to form solid spheres, dissolution-recrystallization to form hierarchical structures subsequently, and an Ostwald ripening process to shape the desired concaves finally. Under visible-light irradiation, complete degradation of Rhodamine B is achieved within 180 min in the presence of Sb2WO6 hierarchical structures, which could be ascribed to the porous structures, high BET surface area (42.58 m(2) g(-1)) and wide absorption in the visible-light region.