Experimental and DFT Investigation on the Ultra Selective Determination of Hg2+ Ion in Water Implementing a PAni-RR5B Composite Modified GCE Electrode

An efficient electrochemical sensor with high sensitivity, selectivity, and fast detection ability was developed for the trace level detection of Hg2+ ion using polyaniline-reactive red-5B (PAni-RR5B) composite as a recognition layer on the GCE surface. The structure and morphology of the produced PAni-RR5B composite were examined using various spectroscopic techniques. The electrochemical features were explored by cyclic voltammetry and electrochemical impedance spectroscopy, whereas the voltammetric sensing behaviour of the modified electrodes was performed by differential pulse voltammetry in different supporting electrolyte mediums. Various sensitivity influencing factors, such as chemical and electrochemical parameters, including the effect of pH, stripping of metal ions, scan rate, and the effect of supporting electrolyte medium, were also determined to enhance the effectiveness of the proposed sensor. The PAni-RR5B/GCE shows the remarkable selectivity and sensitivity towards Hg2+ ion with a low detection limit of 2.59 nM (S/N = 3) for Hg2+ ion in the ranges of 1 to 20 mu M in 0.1 M HCl medium compared to the proposed electrolyte medium, which attributes to the strong binding affinity of PAni-RR5B composite with Hg2+ metal ion. The proposed methodology allowed an ultra selective and sensitive inspection of Hg2+ ions in lake and tap water, making this platform methodology applicable for the detection of various poisonous metal ions due to excellent properties of receptor species such as fast electron transfer kinetics, broad surface area, and exceptional electro-catalytic properties.