Nonhydrolytic sol–gel and gram-scale synthesis of surfactant-free maghemite nanoparticles with high surface area

• Published in: Journal of sol-gel science and technology Vol. 71; no. 3; pp. 606 - 610
• Main Authors: Bae, D. R., Lee, Y.-J., Kim, D. K., Lee, S. W., Chang, K. S., Yi, G.-R., Lee, G.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2014; Springer; Springer Nature B.V
• Subjects: Brief Communication; Catalysis; Ceramics; Chemical synthesis; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Exact sciences and technology; General and physical chemistry; Glass; Inorganic Chemistry; Iron oxides; Liquid phases; Materials Science; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Organic chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Precursors; Sol-gel processes; Surface area; Surfactants; Surfactant-free; High surface area; Cone angle; Nonhydrolytic reaction; Synthesis; Nanoparticle; Sol gel process; Surface area; Maghemite
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-014-3433-2

An organic molecule was used as a surfactant for nanoparticle synthesis in liquid phase. However, residual molecules on the surface of the nanoparticles limit their catalytic applications, because the interaction of a reactant with the nanoparticle surface is interrupted. Therefore, it is favorable for catalytic applications that the organic molecule used in the synthesis of nanoparticles only induces a sol–gel reaction of the metal precursors and the formation of nanoparticles and hardly adheres to the resulting nanoparticles. Herein, we report surfactant-free and high-surface area maghemite nanostructures via nonhydrolytic sol–gel reaction. Using Fe(acetylacetonate) 3 as an iron precursor and hexylamine as a solvent and growth inhibitor, Fe 2 O 3 nanoparticles were generated by nonhydrolysis of the iron complex and condensation at 140 °C under an air atmosphere. Characterization revealed monodisperse nanoparticles with an average size of 2.3 nm and a crystalline phase of maghemite. Residual hexylamine is hardly observed, and thus their specific surface area is 403.7 m 2 /g. An experimental comparison of the Fe 2 O 3 synthesis with hexylamine and benzylamine indicates that the cone angle of an organic molecule is an important factor in the synthesis of nanoparticles with a small size and high surface area.