Electropolymerization of ortho-phenylenediamine and its use for detection on hydrogen peroxide and ascorbic acid by electrochemical impedance spectroscopy

• Published in: International Journal of Electrochemical Science
• Main Author: Ariffin A.; O'Neill R.D.; Yahya M.Z.A.; Zain Z.M.
• Format: Article
• Language: English
• Published: 2012
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84872836755&partnerID=40&md5=105fdc9a76f37e8aeae8ccb490f936ca

Poly(ortho-Phenylenediamine) was deposited as a thin film by electrochemical impedance spectroscopy (EIS) and compared to cyclic voltammetry (CV) on Teflon insulated Platinum-Iridium (Pt) disk microelectrode (125 μm diameter) in 300 mM phosphate buffer solution (pH 7.2). This study focuses on the electropolymerization process and electrical properties of PoPD-modified microelectrodes, using EIS technique. The estimated thickness of the PoPD film was 31 nm with conductivity of 1.1 × 10-5 Scm-1. The initial impedance plot shows a semicircle which characterized the charge-transfer resistance at the microelectrode/polymer interface at higher frequency and a diffusion process at lower frequency. Impedance data were fitted to the Randles and a modified Randles circuit models with X2 = 0.12 and X2 = 0.06 respectively. The capacitive behavior (phase angle = 83°) of the bare Pt microelectrode was transformed to a resistive behavior (phase angle = 13°) after the formation of PoPD layer at lower frequency. The modified electrode was applied as an analytical probe to detect of hydrogen peroxide (H2O2) and ascorbic acid (AA). The EIS technique also revealed that the PoPD layer blocked the AA species, reflected in the higher impedance observed compared to H2O2. © 2012 by ESG.