Electrochemical characterization of functionalized magnetite nanoparticles with pyrogallol on a Au electrode

One reason for the interest in surface modification of magnetite nanoparticles is to create a physical barrier that inhibits their agglomeration and enhances their dispersion. The other reason is to provide different functionalities to the surface. Various functional groups, such as silanes, amines, and hydroxyls, have been successfully utilized as alternatives to functionalize the surface of magnetite. In this study, pyrogallol was selected to be chemically bonded to the surface of magnetite nanoparticles by bridging two of its hydroxyl groups to the iron of magnetite, leaving one extra hydroxyl group in the molecule for further electrochemical characterization. Therefore, we investigated the electrochemical behavior of pyrogallol in solution and when attached to magnetite nanoparticles. Our results include cyclic voltammetry and chronoamperometry of pyrogallol in solution and on pyrogallol-modified magnetite nanoparticles in media with different pH values on a gold electrode. The functionalization of magnetite was confirmed by TGA and FTIR techniques. Additionally, the size of the modified magnetite-pyrogallol nanoparticles was determined by TEM. The attached pyrogallol molecules on modified magnetite-pyrogallol nanoparticles allowed for the production of a stable colloidal suspension that prevented oxidation and agglomeration. We detailed a mechanism of oxidation of pyrogallol that is consistent with the experimental electrochemical results. Finally, we presented an electrochemical characterization of modified pyrogallol-modified magnetite nanoparticles in supernatant and centrifuged solutions.