Eco-friendly silver nanoparticle-based dual sensors for environmental toxicants: Hg²⁺ and H₂O₂

Monitoring mercury ions (Hg²⁺) and hydrogen peroxide (H₂O₂) in aquatic environments is essential due to their environmental persistence and ability to induce severe health disorders. This study highlights the potential of biogenically synthesized silver nanoparticles (AgNPs) as an efficient probe for Hg²⁺ and H₂O₂ detection in water. The AgNP nanoprobes are highly selective for Hg²⁺, as evidenced by the surface plasmon resonance (SPR) band and a visible color shift from brown to colorless; interference studies confirmed minimal responses to competing ions. The nanoprobe exhibited a limit of detection (LOD) of 1.65 µM and a limit of quantification (LOQ) of 5.50 µM, with excellent linearity (R ² = 0.9919). The nanoprobe was tested for Hg²⁺ in real water samples and showed excellent recovery rates. Analysis using synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) showed that the formation of an amalgam during detection alters the SPR. Additionally, the AgNP probe efficiently detected hydrogen peroxide (H₂O₂) in aqueous solution, with an LOD of 5.46 µM and an LOQ of 18.20 µM, respectively. The study emphasizes that a rapid, eco-friendly colorimetric sensor was developed to reliably detect hazardous pollutants in water.