Single-crystalline α-Fe2O3 with hierarchical structures: Controllable synthesis, formation mechanism and photocatalytic properties

A dual iron precursors system in a hydrothermal process was developed for controllable fabrication of α-Fe2O3 hierarchical structures with different morphologies. Micro-pines, snowflakes and bundles were successfully synthesized simply by tuning the total concentration of the two iron precursors K4[Fe(CN)6] and K3[Fe(CN)6] and their molar ratio. The obtained α-Fe2O3 hierarchical structures were characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis. The effect of experimental conditions on the morphologies of the α-Fe2O3 crystals was systematically investigated. A possible formation mechanism of different α-Fe2O3 hierarchical structures was proposed. Good photocatalytic properties were observed for all the hierarchical structures.