Abstract:
Polyaniline-nickel(II)oxide (PANI/NiO) nanocomposites was prepared using in-situ
polymerization method. The structural properties of as produced PANI, NiO and PANI/NiO
nanocmposte were characterized by employing X-ray diffraction (XRD), infrared absorption
(FT-IR) and UV–visible spectroscopy (UV–vis). The XRD pattern indicated semi-crystalline
phase in PANI but crystalline phase for NiO and PANI/NiO nanocmposite. In addition to this,
elelectrochemical behavior of glassy carbon (GC) electrode modified by PANI, NiO and
PANI/NiO materials was characterized using cyclic voltammetry (CV and electrochemical
impedance spectroscopy (EIS) in 0.1 M phosphate buffer solution. The result showed that the
nanocomposite modified electrode was more electrochemically active than the others due to the
synergetic effect of the catalytic nature of NiO and high conductivity of PANI. It was also noticed
that the electrode revealed a quasi – reversible nature. Moreover, dopamine (DA)
electrochemical nature was studied using PANI/NiO/GCE as working electrode in various scan
rates (20 -90 mV/s). The DA oxidized at (0.180V ) and its diffusion coefficient estimated was 0.45
and showed a quasi –reversible process. Besides, PANI/NiO/GCE was used as electrochemical
sensor for the detection of dopamine in standard solution (1 – 150 µM) at optimum pH =7 using
both CV and differential pulse voltammetry (DPV) at scan rate of 50 mV/s. The composite modified electrode exhibited a linear range 1 M to 80 µM (R = 0.996) and 80 µM to 200.0
M (R = 0.996), and good detection limit of 0.016 M (S/N = 3) for DPV measurement. The
sensor was also used to detect dopamine in real sample (i.e., human urine and serum).
Furthermore, the sensor exhibited good selectivity towards DA since no response to ascorbic
acid (AA) and uric acid (UA), repeatability and stability. Therefore PANI/NiO/GCE sensor can
be a good candidate for the determination of DA in different samples
