Structural characterization of marine macroalgae derived silver nanoparticles and their colorimetric sensing of hydrogen peroxide

The present study investigates the algae-mediated synthesis, characterization, and H₂O₂ sensing ability of silver nanoparticles using Sargassum spp. extract. The synthesized nanoparticles were spherical agglomerates and exhibited an absorbance peak at 418 nm, as analyzed by FE-SEM and UV–vis spectrophotometric analysis. TEM-SAED analysis interpreted the size between 2 and 35 nm and crystallinity corresponding to face-centered cubic (FCC) silver structure. This was further supported from XRD findings, which ascertained the presence of (111), (200), (220), and (311) lattice planes. FT-IR analysis confirmed the capping of algal phenolics as corresponding functional groups, which was further confirmed by XPS studies. The nanoparticles were observed to be highly stable in aqueous suspensions, due to the zeta potential value (−22.6 mV). On incubation of synthesized nanoparticles, with H₂O₂ solutions, decolorization of nanoparticle solution was observed along with the reduction of absorbance peak at 418 nm. This color change could be utilized for H₂O₂ detection in contaminated samples. Therefore, this study reveals the potential of sustainable Sargassum spp. biomass in synthesizing beneficial silver nanoparticles which could be exploited for environmental detection applications.