Ternary hybrid of polyaniline-alanine-reduced graphene oxide for electrochemical sensing of heavy metal ions

An efficient electrochemical sensor based on reduced graphene oxide decorated with alanine and polyaniline was developed for the real-time analysis of heavy metal ions (Cd2+, Pb2+, and Cu2+). The morphological and structural analysis of as-synthesized nanocomposite was conducted via X-ray diff;raction approach (XRD), UV/Visible analysis, Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The electrochemical characteristics of the electrode modifiers were examined through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using standard potassium ferrocyanide as a redox probe. Various sensitivity influencing factors such as chemical and electrochemical parameters including pH effect, deposition potential, deposition time and effect of supporting medium were also determined to enhance the effectiveness of the designed sensor. The interference ability of the designed sensor was also studied in the presence of various inorganic and organic species. Proposed methodology endorsed the sensitive and robust analysis of the toxic metal ions with a remarkable low detection limit of 0.03 nM, 0.045 nM and 0.063 nM for Cd2+, Pb2+, and Cu2+ ions, in the linear range of 100 nM–0.08 nM respectively. The proposed method exhibited high sensitivity and selectivity towards Cd2+, Pb2+, and Cu2+ ions detection which can be attributed to the strong binding affinity of rGO/Ala/PANI nanocomposite with these target metal ions. These results suggested that this methodology can be applied for sensitive detection of other organic and inorganic pollutants in water samples.