Biosynthesis of magnetic ZnO@Fe2O3 nanocomposites decorated with Ag/AgCl using Hormoz Island’s red soil and Avicennia marina leaf extract

The development of environmentally sustainable and non-toxic visible-light (VL) sensitive nanostructured photocatalysts is a significant focus in nanotechnology, necessitating safe synthesis techniques for these nanocomposites. This study introduces a straightforward and low-temperature biosynthesis process using leaf extract from the Avicennia marina mangrove (MTLE) and red soil from Hormoz Island, Iran to produce Ag/AgCl-decorated magnetic ZnO@Fe₂O₃, a plasmonic triple heterojunction nanocomposite (NC). The biosynthesized Ag/AgCl/ZnO@Fe₂O₃ magnetic NC (BSNC) exhibited a particle size of ~ 60 nm, a magnetization of 8.04 emu.g^-1, and a band gap energy (Eg) of 1.3 eV, optimized at an MTLE concentration of 0.5 g·100 mL^-1. The concentration of MTLE significantly influenced the properties of the products, acting as a reducing and stabilizing agent. As MTLE concentration increased from 0.125 to 0.5 g·100 mL^-1, VL light absorption intensity improved, alongside changes in Eg, suggesting an optimal concentration for enhanced photocatalytic activity. The BSNC demonstrated a broad absorption peak between 400 and 600 nm, attributed to surface plasmon resonance and electron dynamics involving Ag/AgCl and ZnO. This biosynthetic approach offers an eco-friendly alternative for producing Ag/AgCl/ZnO@Fe₂O₃ plasmonic NCs with improved VL photo-activity.