Surfactant-free hydrothermal synthesis of flower-like BiOBr hierarchical structure and its visible light-driven catalytic activity towards the degradation of sunset yellow

Flower-like BiOBr hierarchical structures were successfully prepared by a facile and surfactant-free hydrothermal method. The as-synthesized products were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS). The characterization results showed that the as-synthesized products were tetragonal phase pure BiOBr and demonstrated well-crystalline with good optical properties. It was also observed that the as-synthesized products were accumulated by large amount of interleaving nanosheets and formed an open porous structure through oriented aggregation. Under visible light irradiation, the as-synthesized products exhibited much higher photocatalytic activity compared to commercial TiO₂-P25 for sunset yellow degradation. Such enhancement was attributed to the unique hierarchical porous surface structure of flower-like BiOBr with good visible light absorption ability which can enhance the generation and separation of electron–hole pairs and led to high yield of hydroxyl radicals quantities as evidenced by the photoluminescence spectra. Moreover, the photocatalytic studies showed that various effects of parameters exerted their individual influence on the degradation of sunset yellow. Furthermore, the as-synthesized products were reused several times without appreciable loss of activity, showing great potential for practical applications in environmental remediation.