Hydrothermal Synthesis of Novel Uniform Nanooctahedral Bi₃(FeO₄)(WO₄)₂ Solid Oxide and Visible-Light Photocatalytic Performance

For the first time, novel single-phase octahedral Bi₃(FeO₄)­(WO₄)₂ (BFW) nanocrystals, as a visible-light-induced catalyst, had been successfully synthesized in a facile alkaline hydrothermal way without using any template. Scanning electron microscopy (SEM) images clearly show single crystals of BFW with regular octahedral morphology. The formation of the single-phase BFW compound was recorded using an X-ray diffraction (XRD) technique. The optical property of BFW was investigated using ultraviolet–visible light (UV-vis) spectra. The band-gap energy of BFW was revealed to be 1.98 eV. More importantly, the interfacial interaction of W⁶⁺ ions substituted by Fe³⁺ ions was confirmed. Moreover, the present study pointed out the positions of the valence band and the conduction band. Compared with the Bi₂WO₆ (BW) sample, BFW exhibited superior photocatalytic degradation activity of the Rhodamine B (RhB) under visible-light irradiation. A trapping experiment was conducted to further illustrate that hydroxyl radicals (•OH) played a distinct role among active species during the photodegradation of RhB.