Highly efficient photocatalytic performance of BiI/Bi₂WO₆ for degradation of tetracycline hydrochloride in an aqueous phase

Abstract

A series of novel BiI/Bi₂WO₆ nanosheets was successfully synthesized using a simple and efficient one-step hydrothermal method; the obtained specimens were subsequently characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectrophotometry, X-ray photoelectron spectroscopy, N₂ adsorption/desorption isotherms, Raman spectroscopy, ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence, and electronic impedance spectroscopy testing. The results indicated that the photocatalytic performance of the BiI/Bi₂WO₆ composites for the degradation of tetracycline hydrochloride (TC) from aqueous media under visible light irradiation (<i>λ</i> > 420 nm) was higher than that of pure Bi₂WO₆. The 0.8I-BiI/BWO composite (where 0.8 is the I : W molar ratio) presented the best photocatalytic performance of all analyzed specimens, and was able to degrade approximately 90% of the TC in 80 min. In addition, radical-capture experiments have demonstrated that superoxide anion radicals and hydroxyl radicals were the main active species for degrading organic pollutants, and a photocatalytic mechanism for the BiI/Bi₂WO₆ system was proposed. This study not only provides a method for the simple preparation of BiI/Bi₂WO₆, but could also present important implications for ecological risk management and prevention against antibiotic pollution.