Magneto-controlled Quantized Electron Transfer to Surface-confined Redox Units and Metal Nanoparticles

Abstract

Hydrophobic magnetic nanoparticles (NPs) consisting of undecanoate-cappedmagnetite (Fe3O4, average diameter ca. 5 nm) are used to control quantized electron transferto surface-confined redox units and metal NPs. A two-phase system consisting of anaqueous electrolyte solution and a toluene phase that includes the suspended undecanoate-capped magnetic NPs is used to control the interfacial properties of the electrode surface.The attracted magnetic NPs form a hydrophobic layer on the electrode surface resulting inthe change of the mechanisms of the surface-confined electrochemical processes. Aquinone-monolayer modified Au electrode demonstrates an aqueous-type of theelectrochemical process (2e- 2H+ redox mechanism) for the quinone units in the absence ofthe hydrophobic magnetic NPs, while the attraction of the magnetic NPs to the surfaceresults in the stepwise single-electron transfer mechanism characteristic of a dry non-aqueous medium. Also, the attraction of the hydrophobic magnetic NPs to the Au electrodesurface modified with Au NPs (ca. 1.4 nm) yields a microenvironment with a low dielectricconstant that results in the single-electron quantum charging of the Au NPs.

Keywords

• Hydrophobic magnetic nanoparticles (NPs) consisting of undecanoate-capped magnetite (Fe3O4
• average diameter ca. 5 nm) are used to control quantized electron transfer to surface-confined redox units and metal NPs. A two-phase system consisting of an aqueous electrolyte solution and a toluene phase that includes the suspended undecanoate- capped magnetic NPs is used to control the interfacial properties of the electrode surface. The attracted magnetic NPs form a hydrophobic layer on th