Hydrothermal synthesis and properties of controlled α-Fe2O3 nanostructures in HEPES solution

Abstract

A facile, template-free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α-Fe2O3 nanostructures in HEPES solution (HEPES=2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl3 molar ratio, pH value, reaction temperature, and reaction time on the formation of α-Fe2O3 nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α-Fe2O3 nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α-Fe2O3 and Ag/α-Fe2O3 nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal-supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials. Copyright © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.