Silver-coated magnetite–carbon core–shell microspheres as substrate-enhanced SERS probes for detection of trace persistent organic pollutants

Abstract

Highly active surface-enhanced Raman scattering (SERS) substrates of Ag nanoparticle (Ag-NP) modified Fe₃O₄@carbon core–shell microspheres were synthesized and characterized. The carbon coated Fe₃O₄ microspheres were prepared via a one-pot solvothermal method and were served as the magnetic supporting substrates. The Ag-NPs were deposited by in situ reduction of AgNO₃ with butylamine and the thickness of the Ag-NP layer was variable by controlling the AgNO₃ concentrations. The structure and integrity of the Fe₃O₄@C@Ag composite microspheres were confirmed by TEM, XRD, VSM and UV-visible spectroscopy. In particular, the Ag-NP coated Fe₃O₄@carbon core–shell microspheres were shown to be highly active for SERS detections of pentachlorophenol (PCP), diethylhexyl phthalate (DEHP) and trinitrotoluene (TNT). These analytes are representatives of environmentally persistent organic pollutants with typically low SERS activities. The results suggested that the interactions between the carbon on the microsphere substrates and the aromatic cores of the target molecules contributed to the facile pre-concentration of the analytes near the Ag-NP surfaces.