Eco-friendly CoFe2O4 ferrite nanoparticles prepared using greek yogurt solution: deep insights into optical properties and abnormal semiconductor–insulator–semiconductor transitions for optoelectronics and catalytic applications†

This study introduces a green and cost-effective synthesis method for CoFe₂O₄ nanoparticles using Greek yogurt, showcasing significant advancements in surface and interface science. The nanoparticles, characterized by a spinel structure with direct and indirect band gaps of 1.46 eV and 0.9 eV, respectively, demonstrate exceptional structural, optical, dielectric, and catalytic properties. Dielectric analysis reveals strong frequency- and temperature-dependent behaviour, with high dielectric constants at low frequencies and conduction mechanisms dominated by polaron hopping and defect states. Using the Havriliak–Negami model, the study highlights temperature-dependent relaxation times and dielectric constants, further elucidating the nanoscale interfacial dynamics governing these phenomena. The nanoparticles achieved a remarkable 97% degradation of H₂O₂ in just 150 minutes at room temperature, following first-order kinetics with a rate constant of 3.39 × 10⁻⁴ s⁻¹. The superior performance is attributed to their high surface area (269.67 m² g⁻¹) and small crystallite size (14.78 nm), which optimize their surface and interface properties. By integrating green synthesis methods with advanced insights into interfacial processes, this work bridges the critical link between nanoscale structural features and functional outcomes, establishing CoFe₂O₄ nanoparticles as ideal candidates for environmentally sustainable optoelectronic and catalytic technologies. This research redefines the intersection of green chemistry and material science, emphasizing the transformative potential of tailoring nanoscale interfaces to drive next-generation sustainable technologies. The findings expand the fundamental understanding of material interfaces and highlight practical pathways for optimizing stability and efficiency in real-world applications, paving the way for breakthroughs in optoelectronics and catalysis.