Kill two birds with one stone: To reduce toxicity and enhance photodegradation of antibiotics by lead cesium bromide via tin doping

Inorganic perovskite lead cesium bromide (CsPbBr3) has attracted great attention due to its excellent photocatalytic capability. However, the intrinsic toxicity of Pb hindered its wide application in photo-electric fields. Herein, an effective modification on the CsPbBr3 was proposed by substituting toxic Pb with low-toxic element Sn, and Sn-doped CsPb1-xSnxBr3 perovskites were synthesized by the simple anti-solvent precipitation which showed improved visible-light photodegradation of antibiotic residue in ethanol. The partially substituted CsPb1-xSnxBr3 (x = 0, 0.3, 0.4, 0.5, 0.6, 0.7, 1.0) perovskite can reduce the toxicity of Pb-based perovskite without destroying the initial structure. The CsPb0.5Sn0.5Br3 displayed a maximum photocatalytic efficiency for the degradation of tetracycline hydrochloride (TC-HCl) (79 %, 60 min). The reaction rate constant was calculated to be 0.1201 min−1, which was 2.0 and 28.8 times higher than the pure CsPbBr3 and CsSnBr3, respectively. Cycling tests showed a minor decrease (<5 %) in the degradation of TC-HCl after four cycles. As confirmed by the photo-electrochemical test, the introduction of Sn results in improved charge separation and transfer. Additionally, holes (h+) and superoxide radicals (∙O2−) played major roles in the photodegradation of TC-HCl based on capture experiments. This work represents a promising approach to reducing the toxicity of metal halide perovskite with optimized activity for efficiently treating antibiotics simultaneously, which may contribute to a breakthrough in new applications such as environmental control.