Dielectric Constant of Poly (ortho-Phenylenediamine) Modified on Pt disk Microelectrode in Presence of Hydrogen Peroxide and Ascorbic Acid

The modified Pt microelectrode with Poly(ortho-Phenylenediamine), PoPD layer was successfully electropolymerized and characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS). The PoPD layer is formed in optimum condition of 300 mM ortho- Phenylenediamine (oPD) with neutral Phosphate Buffer Solution (PBS) at applied potential, +0.5 V. Using EIS technique; the PoPD modified electrode was applied as analytical probe in detecting the oxidation of Hydrogen Peroxide (H2O2) and Ascorbic Acid (AA). The irreversible oxidation current of H2O2 and AA are exhibits on voltammogrames on Pt bare electrode. However, the oxidation peak current for AA diminished on PoPD modified electrode as a result of PoPD layer blocked the electron transfer. It further confirmed by electrochemical impedance spectroscopy by applied lower potential at +0.2 V. In Nyquist impedance plot is characterized by semicircle that represents the charge transfer resistance of oxidized species. It is found that, the PoPD layer was able to blocked AA species which exhibited higher impedance compared to H2O2. Dielectric constant of PoPD modified electrode also was determined in presence AA and H2O2 analytes. A rough morphology of PoPD layer onto the microelectrode was also observed by FESEM.