Controlled synthesis of Bi2NbO5F plates with exposed {010} facet by molten salt method and their photocatalytic mechanism insights

Although the preparation of Aurivillius-type oxyfluoride compounds as photocatalysts has been reported, the control synthesis of Bi 2 NbO 5 F with the exposed highly active facets is still challenging. Herein, the pure Bi 2 NbO 5 F plates have been successfully synthesized through a novel molten salt strategy. Compared to Bi 2 NbO 5 F prepared by solid state method (BF S), the Bi 2 NbO 5 F obtained by molten salt method revealed better crystallinity and purity. Transmission electron microscope (TEM) and corresponding selected area electron diffraction (SAED) confirm that the main exposed facet of Bi 2 NbO 5 F plates is {010} facet. Density functional theory (DFT) calculations indicated Bi 2 NbO 5 F crystal belongs to direct-gap semiconductor and its {010} facet was the most active facet due to its highest surface energy. The Bi 2 NbO 5 F sample with exposed highly active {010} facet exhibited promoted photocatalytic activity for degradation of tetracyclines (TC) and rhodamine B (RhB) in water as compared to the BF S. The free radical capture experiments prove that O 2 − , OH and h + are the main active radicals. The Bi 2 NbO 5 F plates with exposed {010} facet still had high photocatalytic activity even after four cycles. Finally, the possible mechanism of Bi 2 NbO 5 F nanoplate for photocatalytic degradation of pollutants was proposed.