Highly Selective and Sensitive Electrochemical Sensor for Mercury(II) Detection Using Nickel(II) (Bromophenyl)porphyrin on a Glassy Carbon Electrode for Environmental Monitoring

Heavy metal ion pollution poses a significant threat to environmental and human health. We developed a highly selective and sensitive electrochemical sensor for Mercury(II) detection, utilizing a synthesized nickel(II) complex, [(5,10,15,20-tetrakis(p-bromophenyl)porphyrinato] Nickel(II) [Ni(TBrPP)]. The structural integrity, composition, and physicochemical properties of [Ni(TBrPP)] were characterized using a comprehensive set of analytical techniques, including Proton nuclear magnetic resonance, UV–vis spectroscopy, and infrared spectroscopy, confirming structural integrity and optical properties. Its chemical structure and functional groups were elucidated, and its photophysical properties were investigated to assess optical behavior and electronic transitions. Electrochemical performance of the sensor was evaluated using cyclic voltammetry and differential pulse voltammetry, revealing an optimal response at pH 5. The sensor demonstrated exceptional selectivity for Mercury(II), exhibiting minimal interference from competing metal ions such as Cadmium(II), Zinc(II), Copper(II), Manganese(II), and Lead(II) at 10 μM concentrations. With a detection limit of 6 nM, a linear response range of 0.006–10 μM, and a sensitivity of 6.939 μA μM −1 , the sensor proves highly effective for Mercury detection. Excellent stability and reproducibility in real sample analysis yielded recovery rates between 96% and 103%, underscoring its robustness and accuracy for practical applications.