Eco-Engineered Multifunctional ZnFe₂O₄ Nanoparticles: Catalysts for Clean Environments and Crime Scene Clarity

Background: The development of eco-friendly nanomaterials is essential for sustainable environmental remediation and forensic applications. Zinc ferrite (ZnFe₂O₄) nanoparticles have gained interest due to their magnetic, optical, and catalytic properties. This study explores the green synthesis of ZnFe₂O₄ nanoparticles using Phyllanthus emblica (Amla) extract as a natural reducing and stabilizing agent. Methods: ZnFe₂O₄ nanoparticles were synthesized via a green approach and characterized using X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), high-resolution transmission electron microscopy with selected area electron diffraction (HRTEM-SAED), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX), Fourier transform infrared spectroscopy (FTIR), and zeta potential analysis. Their functional properties were further evaluated through antibacterial assays against Staphylococcus sp., Bacillus sp., Klebsiella sp., and E. coli, and latent fingerprint visualization tests on non-porous surfaces under visible and UV light. Results: Characterization confirmed the formation of spinel-structured ZnFe₂O₄ with good crystallinity, an average particle size of 18–20 nm, and a band gap of 1.87 eV. The nanoparticles demonstrated high photocatalytic degradation of malachite green dye—98.5% at 5 mg/L and 97.3% at 20 mg/L within 20 minutes under visible light. Additionally, they exhibited significant antibacterial activity and enhanced latent fingerprint visualization capabilities. Conclusion: The green-synthesized ZnFe₂O₄ nanoparticles exhibit promising multifunctional performance, offering a sustainable solution for environmental remediation and practical applications in forensic science.