SERS self-monitoring of Ag-catalyzed reaction by magnetically separable mesoporous Fe3O4@Ag@mSiO(2)

Well-dispersed Fe3O4@Ag@mSiO(2) nanoparticle was fabricated by encapsulating Ag into yolk-shell structured Fe3O4@mSiO(2) composed of superparamagnetic Fe3O4 core and mesoporous SiO2 shell with bi-solvent nano casting technique using AgNO3 as the precursor. Ag can dwell in both the cavity between Fe3O4 and mesoporous SiO2 as an asymmetric shell and the mesoporous channel, or exclusively fill the cavity through increasing the reduction temperature of AgNO3 from 350 to 550 degrees C. The asymmetric Ag shell proves to be high SERS-sensitive for the detection of methyl blue dispersed in ethanol solution as assisted by magnetically separation, with an enhanced factor of 5.02 x 10(4). The SERS self-monitoring NaBH4 reduction of p-nitrothiophenol catalyzed by Ag nanoclusters in the pore channel was further in situ and real-time achieved with an excellent recyclability.