Synthesis of hierarchical hollow nest-like WO3 micro/nanostructures with enhanced visible light-driven photocatalytic activity

Highlights: • Novel hollow nest-like WO3 micro/nanostructures are successfully fabricated and a possible growth mechanism is proposed. • Annealing temperature improve the photocatalytic activity by adjusting the specific surface area. • The effects of HMTA and pH on morphology is discussed and the mechanism is explored. -- Abstract: Novel hierarchical hollow nest-like WO₃ micro/nanostructures (HNWMs) were prepared via a facile hydrothermal method. These nanostructures were successfully synthesized without using any templates or surfactants. The photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersion spectroscopy (EDX), X-ray and photoelectron spectroscopy (XPS), thermogravimetric analysis/differential scanning calorimetry (TG/DSC), and Brunauer–Emmett–Teller (BET) measurements. We found that the HNWMs are assembled of a number of regular-shaped nanosheets with an average thickness of approximately 30–40 nm. Based on detailed time-dependent experiments, a possible formation mechanism is proposed. The effects of annealing conditions on the structure and photodegradation properties of the HNWMs are investigated. Furthermore, the effect of hexamethylenetetramine (HMTA) on the structure of HNWMs is studied under the same conditions. In addition, the as-prepared HNWMs are found to exhibit excellent photocatalytic activity towards an aqueous solution of tetracycline (TC) and possess good stability and reusability under visible light. This study provides a reliable strategy for the simple and controllable preparation of hollow photocatalysts for use in wastewater treatment.