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-Fe3O4 shell NP, a.k.a., magnetoplasmonic (MagPlas) NP, two porous shell models were prepared: i.e., Ag@Fe3O4 NPs and its SiO2-covered NPs (Ag@Fe3O4@SiO2). We suggested using cyclic voltammetry (CV) to provide unprecedented insight into the porosity of the coreshell NPs caused by the applied potential, resulting in the selective redox activities of the core and porous shell components of Ag@Fe3O4 NPs and Ag@Fe3O4@SiO2 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 (mu A) of Ag to Ag+ in the porous shell to that in the SiO2 coated (nonporous) shell was 400:3.2. The suggested approach and theoretical background could be extended to other types of multicomponent NP complexes.