Understanding the Role of <scp>l</scp> -Arginine-Induced Microwave Synthesis of a Heterostructured Fe ₃ O ₄ /CuFeO ₂ Nanocomposite for Enhanced Alkaline Electrocatalytic Oxygen Evolution Reaction

A stable, high-performance magnetic spinel/delafossite Fe₃O₄/CuFeO₂ (AR-SF/CD) heterostructured nanocatalyst was synthesized through a one-step microwave combustion (MWC) technique using l-Arginine as a fuel. X-ray diffraction (XRD) identified two phases: orthorhombic Fe₃O₄ and rhombohedral CuFeO₂, with crystallite sizes of 29.5 and 26.8 nm, respectively. The material displayed ferromagnetic behavior with coercivity (<i>H</i>_c = 137 Oe), magnetization (<i>M</i>_s ≈ 29.64 emu g^-1), and retentivity (<i>M</i>_r ≈ 4.94 emu g^-1). N₂ adsorption-desorption isotherm revealed a meso- and macroporous structure with a BET surface area of 27.8 m² g^-1, facilitating active sites for the oxygen evolution reaction (OER). In a 1.0 M KOH solution, the electrocatalysts showed very low overpotentials of 325 and 380 mV at a current density of 20 mA cm^-2 with Tafel slopes of 48.9 and 57.6 mV dec^-1, with a Pt coil and graphite rod counter electrodes. The spectroscopic and electrochemical analysis of the material demonstrated superior performance and high durability, attributed to the combined effect of Fe and Cu cations forming heterostructures and causing structural inversion, suggesting it as a cost-effective alternative for OER in water-splitting applications.