Charge Separation and Catalytic Activity of Fe3 O4 @Ag "Nanospheres"

Nanospheres of Ag-coated Fe3 O4 were successfully synthesized and characterized. Photocatalytic properties of Fe3 O4 @Ag composites have been investigated using steady-state studies and laser pulse excitations. Accumulation of the electrons in the Ag shell was detected from the shift in the surface plasmon band from 430 to 405 nm, which was discharged when an electron acceptor such as O2 , Thionine (TH) or C60 was introduced into the system. Charge equilibration with redox couple such as C60 (●-) /C60 indicated the ability of these core-shell structures to carry out photocatalytic reduction reactions. As well, outer Ag layer could boost charge separation in magnetic core through dual effects of Schottky junction and localized surface plasmonic resonance (LSPR)-powered band gap breaking effect under sunlight irradiation; resulted in higher photocatalytic degradation of diphenylamine (DPA). The maximum photocatalytic degradation rate was achieved at optimum amount of Ag-NP loading to products. Adsorption studies confirmed that degradation of DPA dominantly occurred in solution. Moderately renewability of the nanocatalysts under sunlight was due to oxidation and dissolution of the outer Ag layer.