Synthesis and characterization of successive Z-scheme CdS/Bi2MoO6/BiOBr heterojunction photocatalyst with efficient performance for antibiotic degradation

A novel CdS/Bi2MoO6/BiOBr successive Z-scheme photocatalyst has been synthesized by a solvothermalprecipitation method. The structure, composition, morphology and optical property of the ternary composite were investigated. The maximum degradation rate of CdS/Bi2MoO6/BiOBr for tetracycline hydrochloride (TC) can reach 94.41% under visible light, while its degradation rate was 10.43, 2.89, and 2.43 times higher than that of pure Bi2MoO6, BiOBr and Bi2MoO6/BiOBr, respectively. Besides, the CdS/Bi2MoO6/BiOBr composite showed stable catalytic performance after three successive reuses. The improved photo catalytic and stability could be ascribed to the extended visible-light absorption capability, effective separation of electron-hole pairs and layered stable structure. Photoluminescence spectroscopy and electrochemical impedance spectroscopy proved that the composite had more efficient charge separation efficiency. The energy band structure and free radical capturing experiments proved that the redox reaction mainly occurred in the conduction band of CdS and the valence band of BiOBr in this composite, so a possible successive Z-scheme heterojunction mechanism is proposed. This work also provides a feasible idea for the treatment of TC in wastewater. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel CdS/Bi2MoO6/BiOBr successive Z-scheme photocatalyst with enhanced visible-light absorption capability and efficient charge separation efficiency has been successfully synthesized, showing high degradation efficiency for tetracycline hydrochloride and stable catalytic performance after multiple reuses. The proposed mechanism of redox reaction mainly occurring in the conduction band of CdS and the valence band of BiOBr implies a possible successive Z-scheme heterojunction mechanism for the improved photocatalytic activity and stability.