One-step aromatic acids assisted synthesis of γ-Fe2O3 nanoparticles with large surface area by thermal decomposition of ferric nitrate

Maghemite (γ-Fe2O3) has attracted much attention due to its variety of applications in many areas. However, the current preparation methods of γ-Fe2O3 still involve complicated processes and a high cost, thereby needing improvement. In this study, a novel and facile one-step solid-state method for the preparation of γ-Fe2O3 nanoparticles (NPs) is performed through the thermal decomposition of ferric nitrate (Fe(NO3)3⋅9H2O) and the addition of aromatic acids. Three aromatic acids that have different numbers of carboxyl groups (i.e., benzoic acid, phthalic acid, and trimesic acid) are used as additives and their effects on the formation of γ-Fe2O3 NPs are investigated. Furthermore, the influence of the aromatic acid/Fe(NO3)3⋅9H2O mass ratio and calcination temperature on the structural properties of the products are investigated. The structural properties, morphology, and magnetic properties of the products are analyzed through X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption/desorption measurements, and magnetic measurements. The results show that the addition of aromatic acids to Fe(NO3)3⋅9H2O leads to the formation of γ-Fe2O3 NPs, and has a significant influence on the morphology of γ-Fe2O3 NPs. When the aromatic acid/Fe(NO3)3⋅9H2O mass ratio is greater than 0.5, the addition of the three aromatic acids leads to the formation of pure γ-Fe2O3. The γ-Fe2O3 NPs obtained from benzoic acid/Fe(NO3)3⋅9H2O and phthalic acid/Fe(NO3)3⋅9H2O systems do not show a well-defined morphology. In contrast, the γ-Fe2O3 NPs obtained from the trimesic acid/Fe(NO3)3⋅9H2O system are composed of a porous three-dimensional hierarchical structure and have the largest Brunauer−Emmett−Teller surface area (100.0 m2 g−1).