From Agro-Industrial Waste to Multifunctional Nanomaterials: Antioxidant and Catalytic Properties of Iron-Based Bimetallic Nanoparticles Synthesized with Anacardium occidentale Pericarp Extract

Oxidative stress and industrial water pollution represent critical global challenges that demand the development of sustainable, multitarget remediation platforms. This study addresses the existing knowledge gap regarding the modulation of green-synthesized iron nanostructures by secondary transition metals through the fabrication of silver–iron (AgFe), cobalt–iron (CoFe), and copper–iron (CuFe) bimetallic oxide formulations using Anacardium occidentale L. pericarp extracts as dual-functional reducing and capping agents. Characterization was performed using UV-Vis, DLS, AFM, Raman, FTIR, and XRD techniques to elucidate their structural properties. Our results demonstrate that phytochemicals within the agro-industrial byproduct facilitated the formation of stable, spherical bimetallic oxide nanostructures. The CuFe formulation exhibited the highest catalytic activity, achieving 99.1% conversion/reduction of 4-nitrophenol within 6.3 min. Furthermore, all bimetallic oxide formulations demonstrated superior radical scavenging capacity, as evidenced by FRAP/DPPH assays, confirming the synergistic effect of the secondary metals on electron-transfer kinetics. These findings indicate that the integration of secondary metals significantly enhances the performance of biogenic iron-based oxide nanoparticles. Consequently, this study establishes an eco-friendly protocol for the production of bimetallic oxide nanostructures, providing a robust, dual-purpose platform for both environmental remediation and advanced biomedical antioxidant applications.