Synthesis of biogenic silver nanoparticles using <i>Piper chaba</i> leaf extract for dual-functional applications: Hg( <scp>ii</scp> ) sensing and catalysis

This study reports the green synthesis of biogenic silver nanoparticles (AgNPs) for dual applications in mercury (Hg²⁺) sensing and catalysis. AgNP formation was visually confirmed by a color change and corroborated by a surface plasmon resonance band at 441 nm in UV-vis spectra. FTIR spectroscopy, EDX, TGA, and DLS analyses confirmed phytochemical capping. XRD revealed a face-centered cubic structure with a crystallite size of 17 nm, while SEM and TEM showed monodispersed spherical AgNPs with an average size of 20 nm. The synthesized AgNPs exhibited high sensitivity for Hg²⁺ detection, with visual color changes and UV-vis shifts yielding low detection (14 ppm) and quantification (41 ppm) limits. Furthermore, the AgNPs demonstrated significant catalytic activity in reducing 4-nitrophenol to 4-aminophenol and degrading methyl orange and methylene blue dyes. This green synthesis offers a sustainable alternative to conventional methods for large-scale AgNP production, enabling selective Hg²⁺ detection in wastewater and showcasing its potential for environmental remediation and industrial catalysis.