A High-Performance Electrochemical Sensor for the Simultaneous Detection of Hg²⁺ and Pb²⁺ Ions in Water Using Ultrasensitive PAn-RB3R Composite Modified GCE: Experimental and DFT Modeling Studies

This study herein describes the electrochemical detection of real-time analysis of toxic metal ions, specifically Hg2+ and Pb2+ ions. In this work, a glassy carbon electrode that has been modified with a polyaniline-reactive blue 3R composite (PAn-RB3R/GCE), an efficient electrochemical sensor for detecting Hg2+ and Pb2+ ions in water using differential pulse voltammetry (DPV), is presented. The structures and morphologies of the developed sensors were examined using various spectroscopic and microscopic methods. The EIS and CV studies were used to analyze the electrochemical properties of the electrode modifiers. The electrode modifier’s sensing capability and electrochemical catalytic activity were evaluated using DPV analysis by individually and simultaneously analyzing metal cations in acetate buffer solutions at varying pH levels. Moreover, to examine how the scan rate affected the electrochemical properties of the proposed sensors, their electrochemically active surface area was also studied. The proposed sensor’s interference ability was also investigated in the presence of different harmful metal ions. PAn-RB3R/GCE has impressive limits of detection of 0.011 nM for Hg2+ and 1.6 nM for Pb2+ ions in the linear range 1–22 μM for each metal cation. Similarly, the applicability of DPV was evaluated using real water samples. Notably, recovery rates exceeding 100% across all samples confirmed the reliability of the PAn-RB3R/GCE sensor for detecting Hg2+ and Pb2+ ions in real water matrices. Additionally, density functional theory was employed to elucidate the adsorption mechanism of the proposed sensor. These promising results implied that PAn-RB3R/GCE can be considered a good candidate for application in electrochemical detection devices for harmful Hg2+ and Pb2+ ions.