Facile synthesis of CeO2/carbonate doped Bi2O2CO3 Z-scheme heterojunction for improved visible-light photocatalytic performance: Photodegradation of tetracycline and photocatalytic mechanism.

Abstract CeO2 nanoparticles are successfully loaded on carbonate doped Bi2O2CO3 (CBOC) nanosheets by a facile hydrothermal and low-temperature calcination method. CeO2/CBOC heterojunction shows significantly enhanced photocatalytic activity, when 35 mg of CeO2/CBOC photocatalyst is added to tetracycline (TC) solution (20 mg/L, 100 mL), about 79.5% TC is degraded within 90 min under visible light irradiation, which is much higher than that of original CeO2 and CBOC. According to photoelectrochemical characterization and active radical capture experiments, the Z-scheme electron transfer mechanism is the reason for the significant enhancement of photocatalytic activity. Besides, the XPS results indicate that Ce4+/Ce3+ redox pairs are formed at the contact interface between CeO2 and CBOC, which is conducive to the transfer of photoexcited electrons and production of superoxide radicals. Additionally, the photocatalytic mechanism and possible degradation pathway of TC is proposed through free radical trapping experiments and liquid chromatography-mass (LC-MS) analysis. This study will accumulate experience for the combination of CeO2 and bismuth-based nanomaterials, and provide a feasible way to design wide band-gap bismuth-based photocatalysts, thereby achieving efficient visible light degradation of environmental pollutants.