Nanospherical composite of WO3 wrapped NaTaO3: Improved photodegradation of tetracycline under visible light irradiation

In this paper, WO 3 -wrapped NaTaO 3 nanospheres photocatalysts with different W/Ta molar ratios were successfully prepared via a facile hydrothermal method. The samples were characterized by X-ray diffraction, transmission and scan electron microscopy, X-ray photoelectron spectroscopy, FT-IR spectrum, UV−vis diffuse reflectance spectroscopy, and Barrett−Emmett−Teller technique. The photocatalytic activities for degrading tetracycline hydrochloride under visible light irradiation were examined. The results indicated that the as-prepared NaTaO 3 @WO 3 photocatalysts showed the obvious enhancement in the tetracycline hydrochloride degradation ratio, compared with the pure NaTaO 3 and WO 3 under visible light irradiation. The optimum percentage of NaTaO 3 @WO 3 composites with a 60.88% degradation rate was W:Ta   =   0.3:1 in mole, which was mainly attributed to the effective separation of the photo-generated electron and hole as well as the expanding of the absorption edge to the visible region due to the spherical heterojunction by wrapping WO 3 on the surface of NaTaO 3 . The radicals trapping experiments demonstrated that there were multiple active species during the degrading process of TC. The possible mechanism of tetracycline hydrochloride degradation by NaTaO 3 @WO 3 composite was also proposed.