Comparative investigation of BiOCl0.5X0.5 (X = F, Br, and I) heterojunctions for solar-light driven photodegradation of tetracycline hydrochloride

BiOCl0.5X0.5 (X = F, Br, and I) heterojunctions were prepared via the solvothermal approach to achieve the solar-light induced photodegradation of tetracycline hydrochloride (TCH). The photocatalytic activity of BiOCl coupling with BiOI is greatly affected by the molar ratio of Cl/I. The best photocatalytic efficiency of 97.9 % within 120 min is obtained by flower-like BiOCl0.5I0.5 microspheres with a Cl/I molar ratio of 1:1, and the removal efficiency of TCH over BiOCl0.5I0.5 declines to 93.2 % after five cycles. Compared with BiOCl0.5Br0.5 and BiOCl0.5F0.5, BiOCl0.5I0.5 presents the better photocatalytic activity. Z-scheme junction between BiOCl and BiOI is favorable for the efficient separation and migration of photo-generated charge carriers, and the narrow band-gap structure of BiOCl0.5I0.5 microspheres favors the visible-light harvesting.·O2- plays a vital role in BiOCl0.5I0.5-assisted photocatalytic reaction. However, the change in valance states induced by photo-corrosion is responsible for the solar-light deactivation of BiOCl0.5I0.5.