Green synthesis of biogenic ZrO2 nanoparticles using Ficus pumila leaf extract: A sustainable approach to corrosion inhibition and antioxidant enhancement

The pursuit of sustainable nanomaterials has driven the development of eco-friendly synthesis routes for multifunctional metal oxide nanoparticles. In this study, zirconium oxide (zirconia) nanoparticles (ZrO 2 NPs) were green-synthesized using Ficus pumila leaf extract and evaluated for dual functionality in corrosion protection and antioxidant activity. The nanoparticles were characterized by ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential and gas chromatography–mass spectrometry (GC–MS), confirming a semi-crystalline structure (~49.6% crystallinity) with phytochemical-mediated surface capping. Corrosion inhibition of mild steel in 1 M HCl was assessed using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and weight-loss measurements. The ZrO 2 NPs demonstrated a maximum inhibition efficiency of ~81% (PDP at 30 mg/100 mL), with complementary techniques showing efficiencies between 50–70%, yielding an overall performance of ~73%. Enhanced corrosion resistance is attributed to the formation of a protective nanoparticle film that suppresses both anodic metal dissolution and cathodic hydrogen evolution. Antioxidant assays (DPPH) revealed dose-dependent radical scavenging activity, reaching ~66% inhibition at 100 µg/mL, primarily due to phenolic and flavonoid constituents on the nanoparticle surface. To the best of our knowledge, this is the first report of Ficus pumila -mediated ZrO 2 NPs exhibiting integrated anticorrosive and antioxidant properties, highlighting their potential as green, multifunctional materials for protective coatings and biomedical applications.