Electrochemical Investigation of Porosity in Core-Shell Magnetoplasmonic Nanoparticles.

Porous core-shell nanoparticles (NPs) have emerged as a promising material for broad ranges of applications in catalysts, material chemistry, biology, and optical sensors. Using a typical Ag core-Fe 3 O 4 shell NP, a.k.a., magnetoplasmonic (MagPlas) NP, two porous shell models were prepared: i.e. , Ag@Fe 3 O 4 NPs and its SiO 2 -covered NPs (Ag@Fe 3 O 4 @SiO 2 ). We suggested using cyclic voltammetry (CV) to provide unprecedented insight into the porosity of the core-shell NPs caused by the applied potential, resulting in the selective redox activities of the core and porous shell components of Ag@Fe 3 O 4 NPs and Ag@Fe 3 O 4 @SiO 2 NPs at different cycles of CV. The porous and nonporous core-shell nanostructures were qualitatively and quantitatively determined by the electrochemical method. The ratio of the oxidation current peak (μA) of Ag to Ag + in the porous shell to that in the SiO 2 coated (nonporous) shell was 400:3.2. The suggested approach and theoretical background could be extended to other types of multicomponent NP complexes.