Preparation and application of Ag plasmon BiOCl photocatalyst for removal of emerging contaminants under visible light.

Photocatalytic degradation has been extensively investigated toward the removal emerging contaminants (ECs) from water. In this study, a series of Ag-BiOCl plasmon photocatalysts were synthesized through the photo-deposition of metallic Ag on the BiOCl surface. The effects of plasmon modification on the catalytic performance of bismuth oxychlorides were analyzed. Ag addition did not alter the morphology of BiOCl. With the increasing Ag content, the number of oxygen defects on the catalyst surface first increased and then decreased. Moreover, the surface plasmon resonance effect of Ag suppressed the recombination of electron-hole pairs, promoting the migration and separation of photocarriers and improving the light absorption efficiency. However, the addition of excessive Ag reduced the number of active sites on the BiOCl surface, hindering the catalytic degradation of pollutants. The optimal Ag-BiOCl photocatalyst (Ag ratio: 0.025; solution pH: 9; dosage: 0.8 g/L) achieved 93.8 and 94.9% removal of ciprofloxacin and tetrabromobisphenol A, respectively. The physicochemical and photoelectric properties of Ag-BiOCl were determined through various characterization techniques. This study demonstrates that introducing metallic Ag alters the electron transfer path of the catalyst, reduces the recombination rate of electron-hole pairs, and effectively improves the catalytic efficiency of BiOCl. Furthermore, the pathways of ciprofloxacin degradation products and their biotoxicity were revealed.