Alkali-free synthesis of hexagonal star-like Fe-ethylene glycol (Fe-EG) complex and subsequently decomposition to α-Fe2O3 and Fe3O4/α-Fe/C composites

Abstract

• Hexagonal star-like Fe-EG complex was synthesized by a surfactant-and alkali-free solvothermal method. • Hexagonal star-like α-Fe 2 O 3 and Fe 3 O 4 /α-Fe/C were obtained after thermal treatment. • The saturation magnetisation of α-Fe 2 O 3 and Fe 3 O 4 /α-Fe/C were 17.07 and 86.95 emu g −1 , respectively. • The adsorption capacity of Fe 3 O 4 /α-Fe/C towards Congo red was 230.9 mg g −1 . Using ferric nitrate as iron source, hexagonal star-like Fe-ethylene glycol (Fe-EG) complex was synthesized using an alkali-and surfactant-free solvothermal method. The formation of the Fe-EG complex was attributed to the hydrolysis of ferric ions, the oxidation-reduction between EG molecules and nitric acid derived from the hydrolysis of ferric ions, and the reaction between the Fe-O sheets and the deprotonated hydroxyl and carboxyl groups. Hexagonal star-like α-Fe 2 O 3 and Fe 3 O 4 /α-Fe/C composites were obtained after thermal treatment. The saturation magnetisation of them were 17.07 and 86.95 emu g −1 , respectively. The adsorption of the obtained Fe 3 O 4 /α-Fe/C composites towards Congo red (CR) can be well fitted by the Langmuir model, and the maximum adsorption capacity was 230.9 mg g −1 . The results put forward an effective approach for the synthesis of metal alkoxides with a special microstructures.