Green Synthesis of Silver Nanoparticles Using Biomass of Oroxylum indicum for Its Application in Dye Degradation, Metal Sensing, and Radical Scavenging Activity

Silver nanoparticles (AgNPs), valued for their optical, catalytic, and antimicrobial properties, are increasingly being synthesized via eco‐friendly green approaches. In this study, AgNPs were successfully synthesized using aqueous bark extract of Oroxylum indicum . The formation of AgNPs was confirmed by a distinct color change and a UV–visible absorbance peak at 403 nm. FTIR analysis indicated the involvement of hydroxyl and carbonyl groups in nanoparticle formation, while XRD revealed a face‐centered cubic crystalline structure with dislocation density of 9.63 × 10 −3 nm −2 and average microstrain of 2.47 × 10 −3 nm −2 . SEM analysis showed predominantly spherical nanoparticles with slight agglomeration, and the average grain size of the nanoparticles was found to be 24.93 nm. The synthesized AgNPs exhibited excellent photocatalytic performance, degrading 73% of methylene blue dye within 180 min under sunlight in the presence of H 2 O 2 . Furthermore, they demonstrated selective colorimetric sensing for Hg 2+ and Cu 2+ ions, highlighting their potential in heavy metal detection. Antioxidant evaluation using the DPPH assay revealed that the IC 50 of 29.91 ± 2.47 μg/mL for crude bark and IC 50 of 119.0 ± 2.07 μg/mL for AgNPs. Although O. indicum has previously been reported for the green synthesis of AgNPs with emphasis mainly on antibacterial activity and chemical catalytic reduction reactions, the present study extends existing research by demonstrating sunlight‐assisted photocatalytic degradation of methylene blue dye, selective colorimetric sensing of Hg 2+ and Cu 2+ ions, and comparative antioxidant evaluation within a single O. indicum –mediated AgNP system. Overall, O. indicum –mediated AgNPs show promising applications in environmental remediation, pollutant degradation, and metal ion sensing.