Electrochemical synthesis of belt-like polyaniline network on p-phenylenediamine functionalized glassy carbon electrode and its use for the direct electrochemistry of horse heart cytochrome c

Three-dimension (3D) belt-like polyaniline (PAN) network has been prepared via electrochemical polymerization of aniline on p-phenylenediamine (PDA) functionalized glassy carbon electrode (GCE) using a three-step electrochemical deposition procedure. PDA was covalently binded on GCE via the formation of carbon–nitrogen bond between amine cation radical and the aromatic moiety of GCE surface using electrochemical oxidation procedure. X-ray photo-electron spectroscopy (XPS) and cyclic voltammetry have been performed to characterize the attachment of PDA on GCE. The images of scanning electron microscope (SEM) show that the 3D belt-like PAN network is uniform. The width and thickness of the PAN belt varies in the range of 1.5–5.5 μm and 0.1–0.8 μm, respectively. The distance between the belt-contacts ranges from 2.5 to 15 μm. The 3D belt-like PAN network modified GCE (PAN–PDA/GCE) exhibits an improved electro-activity of PAN at an extended pH up to 7.0. The PAN–PDA/GCE not only immobilizes but also leads to a direct electrochemical behavior of cytochrome c (Cyt c). The immobilized Cyt c maintains its activity, showing a surface-controlled electrode process with the electron-transfer rate constant (ks) of 14.8 s−1 and electron-transfer coefficient (α) of 0.48, and could be used for the electrocatalytic reduction of hydrogen peroxide (H2O2).