One-Step Synthesis of Spherical γ-Fe2O3 Nanopowders and the Evaluation of Their Photocatalytic Activity for Orange I Degradation

Abstract

Maghemite ( γ-Fe ₂O ₃) nanopowders were synthesized under aeration (oxidizing) conditions by aqueous synthesis in this study. The microstructures of the prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-BJH. The XRD analysis and the chemical experiments showed that well-crystallized γ-Fe ₂O ₃ nanoparticles were successfully obtained with a mean particle size of approximately 17 nm. The prepared γ-Fe ₂O ₃ was spherical with a BET surface area of 14.357 m ²/g and a total pore volume of 0.050 cm ³/g. Varying the reaction conditions, such as pH, temperature, and reaction time, we obtained crystallized γ-Fe ₂O ₃ powders with different crystallization extent and different particle sizes. When the pH of the reaction suspension was increased, the reaction time was prolonged, and the reaction temperature was increased, the γ-Fe ₂O ₃ powders underwent superior crystallization and had larger particle sizes. All the obtained γ-Fe ₂O ₃ powders had significant photocatalytic activities under both UV and visible light irradiation for Orange I degradation, and the powders with better crystallization and larger particle size had relatively lower activities for Orange I photocatalytic degradation. The one-step aqueous synthesis method presented in this paper may provide an advantageous pathway to synthesize large quantities of this important iron oxide.