Regulating superoxide radicals and light absorption ability for enhancing photocatalytic performance of MoS2@Z by CeO2 rich in adsorbed oxygen

Nano molybdenum disulfide (Nano-MoS 2 ) can be as a photocatalyst for antibiotic removal under visible light. However, the low energy of visible light and limited radicals restrict the applications of nano-MoS 2 . In this study, ceria dioxide (CeO 2 ) rich in adsorbed oxygen was introduced into MoS 2 @Z (MoS 2 @Zeolite) to synthesize full-spectrum CeO 2 /MoS 2 @Z photocatalysts (CeO 2 /MoS 2 @Zs). The CeO 2 /MoS 2 @Z-3 (Ce: 1.5 mmol; Mo: 3.5 mmol) shows the best photocatalytic ability (98.32%) for tetracycline within 150 min, which is 18.20% improvement over MoS 2 @Z. The UV–vis diffuse reflection spectra of photocatalysts shows that the ultraviolet absorption ability of CeO 2 /MoS 2 @Z-3 improved when CeO 2 was introduced. The active species trapping experiment and electron paramagnetic resonance (EPR) test prove h + and superoxide radicals (•O 2 − ) are the main active species, and CeO 2 rich in adsorbed oxygen improves the amounts of •O 2 − in photocatalytic process. Moreover, singlet oxygen ( 1 O 2 ), producing by oxygen vacancies of CeO 2 , also plays an important role. The enhanced photocatalytic activity is attributed to full-spectrum (200 nm–800 nm) absorption performance , improved content of •O 2 − , and electron-hole (e − /h + ) pairs separation. After five times recycle, the photodegradation efficiency of CeO 2 /MoS 2 @Z-3 only decreased by 2.59%. Meantime, the proposed three photocatalytic pathways show that tetracycline eventually degraded into small organics (like C 5 H 8 O 3 ), H 2 O and CO 2 by dehydration, demethylation, deamination, dihydroxylation, deamidation, ring-opening reaction and carbonylation . The results show that CeO 2 /MoS 2 @Z-3 may become a high efficiency, stable, and promising photocatalyst for tetracycline wastewater treatment .