Supramolecular Microfibrils of O-Phenylenediamine Dimers: Oxidation-induced Formation of Au Nanoparticle-decorated Nanoplates for H2O2 Detection

The direct mix of aqueous FeCl3 and o-phenylenediamine (OPD) solutions at room temperature leads to supramolecular microfibrils of OPD dimers generated by the oxidation of OPD monomers by FeCl3. In this paper, we demonstrate that the subsequent treatment of such microfibrils with a HAuCl4 aqueous solution leads to Au nanoparticle (AuNP)-decorated nanoplates. The possible formation mechanism involved is also discussed. It is found that such nanocomposites can effectively catalyze both oxidization and reduction of H2O2. The sensor constructed with these nanocomposites exhibits a fast amperometric response time of less than 4 s. The linear detection range is estimated to be from 100 μM to 170 mM (r=0.997), and the detection limit is estimated to be 8 μM at a signal-to-noise ratio of 3.