Hierarchical WO3 nanostructures assembled by nanosheets and their applications in wastewater purification

• WO3 microflowers are obtained by simple hydrothermal process at low temperature.
• The prepared WO3 assembles were used as potential photocatalyst.
• Excellent photocatalytic degradation of MB is presented after 5 cycles.

In this work, WO3 hierarchical structures assembled by many nanosheets have been successfully fabricated through a facile and surfactant-free hydrothermal method. Morphologies and microstructures of the as-synthesized products are examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). A possible growth mechanism of the as-obtained WO3 hierarchical structures is proposed by adjusting reaction time and the dosage of Na2SO4. The as-prepared WO3 products are further regarded as a kind of photocatalyst for the photocatalytic degradation of three toxic organic dyes, Methylene Blue (MB), Eosin Red (ER) and Congo Red (CR). In addition, degradation efficiencies of WO3 products with different morphologies towards MB are also investigated, revealing that hierarchical WO3 structures possess preferable photocatalytic performance. It demonstrated that the as-prepared products may be promising application in wastewater purification.