Facile solvothermal synthesis of Ag/Fe3O4 nanocomposites and their SERS applications in on-line monitoring of pesticide contaminated water

Nanocomposites of noble metal and magnetic materials deliver both SERS activity and magnetic properties, and thereby have great advantages for trace analysis in the fields of analytical chemistry, biological and environmental sciences. In this work, Ag/Fe3O4 nanocomposites have been obtained by a facile one-pot solvothermal method. The Fe3O4 nanoparticles (NPs) compounded with Ag possess excellent superparamagnetism, which guarantees an effective self-aggregation of the Ag/Fe3O4 composites. The saturation magnetic moment and SERS activity of the as-prepared nanocomposites are easily optimized by adjusting the mole ratio of silver oleate and iron oleate. The sample with Ag/Fe = 5 possesses optimal SERS performance for both R6G and MB detection. The Fe3O4 NPs with ultra small size behave just like glue or a contractile net, which wrap the Ag NPs together under an external magnetic field and give rise to high-density and high-intensity “hot-spots”. The enhancement factors (EFs) of the sample with Ag/Fe = 5 are over ∼108 both for R6G and MB detection. The as-prepared magnetic nanocomposites have been applied to realize an efficient but convenient real-time on-line monitoring of atrazine in flowing pesticide contaminated water, which show enormous potential in the application of on-line monitoring for industrial and agricultural production.