Simultaneous photocatalytic tetracycline oxidation and chromate reduction via a jointed synchronous pathway upon Z-scheme Bi12O17Cl2/AgBr: insight into intermediates and mechanism

Abstract

The coexistence of heavy metals and antibiotics is not only unprecedently detrimental to modern wastewater but also poses unprecedented challenges to pollution elimination, arousing urgent demand for highly efficient photocatalysts as a solution. Herein, AgBr (AB) nanoparticles were chosen to load onto Bi₁₂O₁₇Cl₂ (B₁₂) nanosheets for their morphology and intrinsic redox potentials. The resultant 2D/0D Bi₁₂O₁₇Cl₂/AgBr (B₁₂/AB) composites were exposed to hexavalent chromium (Cr(VI)) and tetracycline (TC) both individually and simultaneously to examine their removal capacity. Notably, the B₁₂/AB 1 : 1 sample exhibited meritorious photocatalytic activity when exposed to the mixture solution of Cr(VI) and TC, with a boost in Cr(VI) reduction efficiency by 9.2-folds, while the TC degradation was also improved by 9%. The enhancement could be attributed to the 2D/0D morphology observed in TEM images, which provides abundant reaction sites, and the Z-scheme charge transfer pathway that inhibits the recombination of photogenerated charge carriers, while retaining the high redox potentials. Furthermore, the pathway of TC degradation in complex pollutant solutions was investigated with a liquid chromatography (LC) coupled with mass spectrometer (MS). The B₁₂/AB Z-scheme system offers complimentary coordination that creates a jointed synchronous pathway for removing Cr(VI) and TC simultaneously. Therefore, this work could shed more light on the simultaneous photocatalytic removal of heavy metals and organic pollutants in wastewater.