Constructing 3D flower-like Ho3+/Yb3+-codoped BiOCl upconverting microspheres with splendid visible-light driven photocatalytic activities towards ultrafast tetracycline removal

Abstract

Exploring effective strategy to improve visible and near-infrared (NIR) light response of semiconductor photocatalysts is an urgent challenge. Herein, series of 3D flower-like BiOCl and Ho3+/Yb3+-codoped BiOCl microspheres were designed to fulfill the aforementioned issues. Via controlling the reaction time, both the morphology details and photocatalytic behaviors of 3D flower-like BiOCl microspheres are simultaneously manipulated. Moreover, excited by 980 nm light, intense upconversion emissions arising from Ho3+ are observed in 3D flower-like BiOCl microspheres, reaching up to their states when Yb3+ content is 5 mol%. On the other hand, the photocatalytic features of resultant microspheres are systematically investigated by detecting the tetracycline (TC) removal ability under visible-NIR light irradiation. Compared with 3D flower-like BiOCl microspheres, these products doped with Ho3+ and Yb3+ exhibit much better photocatalytic activities, in which the 3D flower-like BiOCl:Ho3+/0.03Yb3+ microspheres can remove 85% of TC within 2 min upon visible light irradiation. Furthermore, the 3D flower-like Ho3+/Yb3+-codoped BiOCl microspheres can also harvest the NIR light to degrade TC. It is found that h+,·O2- and·OH active species are generated during the photocatalytic process. Additionally, the toxic TC can decompose into non-biotoxicity producst by using the designed microspheres to realize wastewater purification. Our currently finding may propose prospective guidance for the preparation of highly efficient photocatalysts via using rare-earth ions doping, morphology control and upconversion emission strategy.