Valorization of Industrial Mill Scales into Multiphase Iron Oxide Nanostructures for Alkaline Water Splitting and Photocatalytic Dye Degradation

Herein, value-added iron oxide nanostructures are successfully synthesized directly from industrial steel mill scale via a simple precursor-free planetary ball milling technique for sustainable hydrogen production and environmental remediation. Comprehensive XRD analysis confirms heterogeneous crystalline phases comprising wüstite, magnetite, and hematite. The waste-derived catalysts demonstrate robust bifunctional electrocatalytic activity toward HER and OER in alkaline media, achieving low overpotentials of 342 and 356 millivolts at ten milliamperes per square centimeter for the hydrogen and oxygen evolution reactions, respectively, alongside favorable Tafel slopes and exceptional long-term operational stability. Furthermore, under natural sunlight, the nanostructures achieve efficient photocatalytic degradation of methylene blue, attaining 86.4 and 89.7 percent degradation efficiencies for 15 and 30 milligrams of catalyst. This comprehensive study successfully converts secondary metallurgy industrial byproducts into highly cost-effective multifunctional nanomaterials, thus presenting an exceptionally promising dual-purpose pathway for green hydrogen generation coupled with advanced industrial wastewater purification and environmental pollution control.