Enhanced photocatalytic activity of Ag-CsPbBr3/CN composite for broad spectrum photocatalytic degradation of cephalosporin antibiotics 7-ACA

A visible-light-induced antibiotics degradation system based on a nano-Ag, CsPbBr3 quantum dot (QDs) and bulk g-C3N4 (CN) ternary assembly (Ag-CsPbBr3/CN) has been firstly constructed under an organic phase environment, oleylamine (OLA) and oleic acid (OA) were used as surfactants to stabilize the CsPbBr3, l-cysteine was used to facilitate the interaction between nano-Ag, CsPbBr3 and CN. The new ternary assembly of Ag-CsPbBr3/CN composite was used to degrade 7-aminocephalosporanic acid (7-ACA) under visible light irradiation, and the 7%-Ag-CsPbBr3/CN composite displayed the superior photocatalytic activity, approximately 92.79% of 7-ACA has been degraded to CO2, H2O and other small molecules at 140 min, which was approximately 1.49-folds, 1.56-folds, 3.01-folds and 11.43-folds higher than 9%-CsPbBr3/CN, 7%-Ag/CN, pure CN and pure CsPbBr3, respectively. A possible mechanism for 7-ACA degradation over Ag-CsPbBr3/CN composite were proposed according to detailed measurements of adsorption test, Brunauer-Emmett-Teller (BET) measurement, UV–vis diffuse reflectance spectra (DRS), photoluminescence spectra (PL), transient photocurrent response and electrochemical impedance spectroscopy (EIS) measurement, and the enhanced photocatalytic activity of Ag-CsPbBr3/CN composite could be attributed to the excellent adsorbability, the enhanced light-harvesting and reduced charge recombination, as well as the synergistic effects of nano-Ag and CsPbBr3 co-loaded with CN. In addition, Holes (h+) and hydroxyl radicals (OH) played major roles, electronic (e−) and superoxide radical (O2-) played minor roles based on the reactive-species-trapping experiments, the NBT transformation and the 7-hydroxycoumarin fluorescent experiments. Furthermore, a possible 7-ACA degradation pathway was investigated based on the Liquid Chromatography-Mass spectroscopy (LC-MS) experiment to better understand the degradation process. The present opens up a new insight for using CsPbBr3 as photocatalyst to degrade antibiotics.