CuO loaded ZnS nanoflower entrapped on PVA-chitosan matrix for boosted visible light photocatalysis for tetracycline degradation and anti-bacterial application

Novel photocatalyst CuO loaded ZnS nanoflower supported on carbon frame work PVA/Chitosan was synthesized by co-precipitation and ultrasonic assisted method. The co-existence of ZnS and CuO and its crystallinity in nanohybrid was verified by XRD, SAED and HR-TEM analysis. The availability of defects in ZnS was identified by EPR. FTIR and TGA verified the presence of PVA and Chitosan. Defects mediated ZnS–CuO/PVA/chitosan heterojunction promote synergistic charge separation with type II interface. Zn-vacancy facilitates two-photon excitation that improves visible-light harvesting. The photocatalytic activity of ZnS–CuO/PVA/Chitosan was 94.7% which is higher when compared to ZnS (40%) and CuO (60%). The photocatalytic mechanism was elucidated using scavenger test and both ·O2− and ·OH were found to play key role in tetracycline degradation. In addition, ZnS–CuO/PVA/Chitosan demonstrated efficient anti-microbial effect against the both gram strains on comparing with individual ZnS and CuO. Thus, the multifunctional ZnS–CuO/PVA/Chitosan is promising for the photocatalytic degradation of tetracycline and as an antimicrobial agent. •Zn-vacancy mediated charge separation and visible-light absorption in ZnS–CuO/PVA/chitosan.•Nanoflowers show remarkable tetracycline photo-degradation up to 94.7% without any cocatalyst.•The retention of strong redox potential e−/h+ pairs could afford to generate more ·O2− and ·OH radicals.•High photo-degradation by visible light-to-energy efficiency could be achieved for ZnS/CuO.•The nanoflowers showed improved bacterial growth inhibition.