Facile construction of 3D CdS-Ag2S nanospheres: a combined study of visible light responsive phtotocatalysis, antibacterial and anti-biofilm activity

Abstract

The CdS/Ag2S nanocomposites (NCs) were synthesized by chemical co-precipitation technique. The optical properties and multifunctionality of the NCs were studied by evaluating photoluminescence, photocatalytic, antibacterial and anti-biofilm properties. The microscopic image indicated that the prepared CdS/Ag2S NCs were spherical shaped. The scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicates the successful formation of CdS/Ag2S NCs which were in nano-size. Brunauer–Emmett–Teller (BET) surface area analysis indicates the high surface area (57.23 m²/g) of NCs with narrow pore size. On comparison with pure Ag2S NPs (1.62 eV), CdS/Ag2S NCs bandgap had shift to 2.12 eV which facilitates visible light sensitization. The energy-dispersive X-ray spectroscopy (EDAX) analysis provides chemical composition details and possible electronic states observed via XPS core level scan of Ag3d, Cd3d and S2p. The activity of CdS/Ag2S NCs photocatalyst was estimated based on methylene blue (MB) dye degradation by irradiating under visible light. NCs showed excellent photocatalytic activity and at pH 8, the particles showed 95 ± 2.4% degradation of MB in 60 min. The ·O2- radical played key role in MB degradation. The CdS/Ag2S NCs exhibited a stable photocatalytic performance after six cycles. Total organic carbon (TOC) analysis of degraded product supported high mineralization of the pollutants. The NCs showed good antibacterial property against S. aureus and E. coli. The precoated CdS/Ag2S NCs showed greater inhibition in biofilm formation. CdS/Ag2S NCs also showed toxic effect on formed biofilm under dark and light condition. The research work testified that CdS/Ag2S NCs have potential applications in environmental treatment and antimicrobial applications.