Abstract:
Fe3O4, ZrO2 and Fe3O4/ZrO2 nanocomposites were synthesized by chemical co-precipitation
method. The structural and morphological properties of the as-synthesized materials were
characterized by FTIR, UV-Vis, XRD and SEM. Results obtained for the nanomaterials
confirmed the formation of Fe3O4, ZrO2 and Fe3O4/ZrO2 nanocomposite. XRD diffraction
patterns depicted Fe3O4, ZrO2 and Fe3O4/ZrO2 crystalline structure and the smaller size of the
nanocomposite (9.8 nm) in comparison to the magnetite (52.11 nm) and zirconium oxide (51.5
nm). Electrochemical properties of carbon paste electrode modified by Fe3O4, ZrO2 and
Fe3O4/ZrO2 nanocomposite were studied using cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS) in the presence of 2 mM K3Fe(CN)6 and aqueous 0.1 M KCl. The
acquired voltammograms demonstrates that Fe3O4/ZrO2 nanocomposite showed the highest
electrochemical signal compared to the bare CPE and the other modified electrodes. This could
be due to the synergistic effect as a result of the high absorption capacity of Fe3O4 and
electrocatalytic properties of ZrO2. The EIS spectra result was also consistent to that of the CV;
CPE modified by the binary system showed a small semicircle (low charge transfer resistance
976 Ω) to that of magnetite 2168 and zirconium oxide 2420 Ω. These behaviors can improve the sensitivity and the response of Fe3O4/ZrO2/CPE proposed sensor for the detection of ascorbic
acid (AA). To improve the performance of the sensor pH and scan rate were optimized. Under
optimized condition (pH = 4 and υ = 100 mV s
-1
) Fe3O4/ZrO2/CPE electrode was applied to
determine the concentration of AA in standard solution (1 to 6 x 10-6 M) using differential pulse
voltammetry. The sensor exhibits good linear range (1 - 6 µM), sensitivity (11 µA/µM) and
detection limit (0.51 µM), reproducibility (2.4 %) and stability (96.91 %). The electrode was also
applied to determine AA in paracetamol. The finding demonstrated the developed sensor can be
a potential candidate for routine analysis of AA in pharmaceuticals, food and fruit samples.
