Conjugated CdS/CNTs/ZnxAg1−xWO4 S-scheme heterostructure for enhanced photocatalytic degradation of antibiotics: Targeting photogenic charge separation and transmission.

Manipulating charge transfer at the nanostructure interface of a S–scheme heterostructure is critical to the photocatalytic performance and practical application. Here, we design a novel S–scheme conjugated photocatalyst CdS/CNTs/Zn x Ag 1−x WO 4 (CZA/CN x) capable of accelerating antibiotic degradation under visible light. Experimental results showed that first-order kinetic constants of CZA/CN x were 1.59, 2.57, and 1.73 times that of CdS/Zn x Ag 1−x WO 4 for amoxicillin degradation, respectively. A series of characterization analysis demonstrated that delocalized π-bonds were existed in a whole composite system (S C–C C···C O) and its could produce a easily excited state of triplet state T 1 instead of lowest singlet excited state S 1 generated from the ground state (S 0). In situ XPS indicated that the electrons will migrate from CdS to ZA/CN x via conjugated redox pathway. Furthermore, this pathway of charge transfer is prevented from the opposite trend, which is depended on establishment of internal electric field and a Schottky barrier in S–scheme conjugated photocatalyst. The density functional theory calculation (DFT) revealed Fermi level of CdS and ZA x were −3.81 eV and −6.80 eV, indicating the conjugated redox pathway of electron transfer is feasible. The successful application of this S–scheme conjugated photocatalyst strategy provide a new direction of conjugated photocatalyst synthesis to address the increasing antibiotic contamination. • A novel S-scheme conjugated CZA/CN x photocatalyst was prepared by a one-step hydrothermal method. • The CZA/CN x photocatalyst for antibiotic degradation is superior to the CZA x photocatalyst. • Delocalized π-bonds leaded dense distribution of energy levels and excite the higher energy state of triplet state T 1. • The possible charge transfer path were proposed for contact interface of CdS and ZA x. [ABSTRACT FROM AUTHOR]