Synthesis, characterization and photocatalytic activity of inexpensive and non-toxic Fe2O3-Fe3O4 nano-composites supported by montmorillonite and modified by graphene

Inexpensive and non-toxic novel Fe2O3-Fe3O4 nano-composites supported by montmorillonite and modified by graphene were successfully synthesized using the liquid phase reduction hydrothermal method. The presence of montmorillonite reduced sizes of iron crystals, and the loading of graphene enhanced the separation efficiency and electron-conductivity of photo-induced electron-hole pairs. The methyl orange degradation experiment was made to investigate the photocatalysis performance of pure Fe2O3-Fe3O4, Fe2O3-Fe3O4-Montmorillonite and Fe2O3-Fe3O4-Montmorillonite-Graphene at the same condition. The absorption of nano-composites was a slight blue-shifted with a decreasing crystallite size of iron nano-particles, while it was clearly shifted toward longer wavelengths upon the modification using graphene. Fe2O3-Fe3O4-Montmorillonite-Graphene exhibited the excellent optical response and photocatalytic activity in visible region: the degradation rate of methyl orange reached 2.77 times faster than that of Fe2O3-Fe3O4 and 1.61 times faster than that of Fe2O3-Fe3O4 Montmorillonite within 30 min irradiation. Results implied that applications of montmorillonite helped to prevent agglomeration of iron nano-particles, and graphene helped to reduce the charge recombination rate, further validated an enhanced photocatalytic performance of Fe2O3-Fe3O4-Montmorillonite-Graphene superiorly. The current study shed new light on synergetic effects of the inexpensive and non-toxic iron oxide nano-photocatalyst with visible-light responsible and magnetic-active compositions, agglomeration-preventive nano-structures by montmorillonite and enhanced electron separation by graphene. (C) 2017 Elsevier Ltd. All rights reserved.