➀ A sustainable method converts orange peel waste into magnetite nanoparticles (Fe₃O₄ NPs) for clean energy applications;

➁ These nanoparticles demonstrate high efficiency in catalyzing the oxygen evolution reaction (OER) for hydrogen production, with a low overpotential of 0.3 V and stability over 2,000 cycles;

➂ The approach offers a cost-effective, eco-friendly alternative to rare metals and shows potential in environmental remediation and medical fields.