Highly Sensitive Detection of Mercury Ions Using Zincophosphite Framework Nanoparticle–Polyaniline Composites

Abstract

This study reports a highly sensitive mercury ion sensor composed of the zincophosphite framework nanoparticle (NTOU4nano) blended with in situ synthesized conductive polyaniline (PANI). High stability of the pristine zincophosphite solid not only renders a facile nanosizing treatment feasible but also allows it to withstand the electrochemical PANI deposition at a low pH condition. PANI significantly enhances the surface coverage concentration and increases the electron transfer capability of the resulting composite. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), hydrodynamic amperometry, and electrochemical impedance spectroscopy (EIS) are used to characterize and optimize the electroanalytical performance of the nanocomposite. The resulting electrochemical sensor shows a linear dynamic range for mercury ion detection ranging from 0.05 to 27.5 nM and exhibits one of the lowest limits of detection (LODs) of 3.49 × 10–11 M reported using crystalline organic–inorganic hybrids. Additionally, the practical utility of the nanocomposite for mercury ion sensing is demonstrated using water samples containing high salt concentrations, as well as from the environment including the seawater and river water. In short, the reported nanocomposite is among one of the first metallophosphite materials being consolidated with PANI as an integrated sensing platform for highly sensitive mercury ion detection and holds good promise for early-warning application.