A novel S-scheme heterojunction of Cd0.5Zn0.5S/BiOCl with oxygen defects for antibiotic norfloxacin photodegradation: Performance, mechanism, and intermediates toxicity evaluation

S-scheme heterojunction structure can endow the photocatalysts with high-performance photo-degradation of pharmaceuticals and personal care products (PPCPs) since it can remain the photogenerated electrons/holes with stronger redox ability. Herein, an integrative S-scheme heterojunction photocatalyst building from Cd 0.5 Zn 0.5 S nanoparticles and BiOCl microflowers with oxygen vacancies (OVs) was developed. Moreover, the in-situ grown process ensures the firm contact and intense electron coupling between BiOCl and Cd 0.5 Zn 0.5 S. As a result, Cd 0.5 Zn 0.5 S/BiOCl exhibited a significant reinforcement of photo-activity and stability for the abatement of antibiotic norfloxacin, manifesting a 2.8-fold or 9.6-fold enhancement compared to pristine Cd 0.5 Zn 0.5 S or BiOCl. Cd 0.5 Zn 0.5 S/BiOCl also shows good resistance to alkaline, sodium salts and humic acid. The performance of Cd 0.5 Zn 0.5 S/BiOCl to photocatalytically degrade other PPCPs with different molecular structures was further confirmed. At last, the ability of Cd 0.5 Zn 0.5 S/BiOCl for PPCPs de-toxicity was verified by evaluating the toxicity of norfloxacin and its degradation intermediate. This study demonstrates a new S-scheme heterojunction photocatalyt for efficient removal of PPCPs as well as provides some insights into developing high-performance metal sulfide solid-solution-based S-scheme heterojunctions for water decontamination.