Synthesis and Characterization of Ag–Fe Bimetallic Nanoparticles and Nanocomposites (Alloys and Core–Shells) for Photocatalytic Degradation of Bromophenol Blue Dye Using <i>Grewia optiva</i> Leaf Extract

ABSTRACT Ag–Fe bimetallic nanoparticles (alloy and core–shell structures) were synthesized using Grewia optiva leaf extract through a green, phytochemical‐mediated approach. The effects of pH, temperature, extract concentration, and Ag:Fe molar ratio on nanoparticle formation were systematically optimized, enabling size‐controlled and morphologically distinct nanostructures. Under optimized conditions (pH 8, 65°C, 3:1 Ag:Fe ratio), the nanoparticles exhibited strong optical properties and enhanced catalytic activity. Photocatalytic degradation of bromophenol blue (BPB) was performed using a 125‐W UV lamp (365 nm) for 90 min, and degradation efficiencies were calculated using absorbance decay following a pseudo–first‐order kinetic model. AgNPs, Ag–Fe alloy, and Ag–Fe core–shells achieved degradation efficiencies of 91%, 88.58%, and 81.47%, respectively. Postphotocatalysis Fourier transform infrared (FTIR), x‐ray diffraction (XRD), and scanning electron microscopy (SEM) confirmed structural stability, and reusability tests demonstrated consistent catalytic performance over three cycles. These findings highlight the potential of G. optiva ‐mediated Ag–Fe nanostructures as cost‐effective and sustainable photocatalysts for dye degradation.