Magnetically Recoverable Antibacterial Silver-Doped Magnetite/Zinc Oxide Core/Shell Composite Nanosheets for Photocatalytic Removal of Pollutants

Abstract

Silver-doped core/shell magnetite/zinc oxide composite perforated nanosheets have been synthesized and characterized by high resolution scanning electron and transmission electron microscopies, energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED), powder X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, solid state electrochemical impedance spectroscopy and UV-visible diffuse reflectance, photoluminescence and time correlated single photon counting (TCSPC) lifetime spectroscopies. All the employed techniques reveal the implantation of nanoparticulate magnetite in silver-doped zinc oxide nanosheets. The length and breadth of the nanosheets run to a few microns. The observed lattice fringes indicate the core/shell structure and silver-doping. The SAED confirms the presence of magnetite, zinc oxide and metallic silver in the nanocomposite. The EDS shows the presence of the constituent elements in the nanocomposite. The XRD and Raman spectrum are characteristic of the Ag-doped zinc oxide shell. The nanocomposite displays moderate absorption of visible light due to the magnetite core and sharp UV-A light absorption because of the zinc oxide shell. The emission spectrum of the nanocomposite is similar to that of pristine zinc oxide which confirms the zinc oxide shell. The TCSPC lifetime spectroscopy shows that the lifetime of charge carriers in zinc oxide shell is not influenced by the magnetite core. The charge transfer resistance of the nanocomposite is less than that of pristine zinc oxide but larger than that of magnetite. The magnetic hysteresis loop reveals the magnetic properties of the nanocomposite. The prepared core/shell composite nanosheets possess photocatalytic activity and mineralize dye efficiently. The synthesized nanocomposite is a bactericide and disinfects E. coli efficiently. Thus the synthesized core/shell nanosheets are two-in-one material - removes organic pollutants without requiring any chemical and disinfects bacteria even in dark.