Single-crystalline alpha-Fe{sub 2}O{sub 3} 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 alpha-Fe{sub 2}O{sub 3} hierarchical structures with different morphologies. Micro-pines, snowflakes and bundles were successfully synthesized simply by tuning the total concentration of the two iron precursors K{sub 4}[Fe(CN){sub 6}] and K{sub 3}[Fe(CN){sub 6}] and their molar ratio. The obtained alpha-Fe{sub 2}O{sub 3} 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 alpha-Fe{sub 2}O{sub 3} crystals was systematically investigated. A possible formation mechanism of different alpha-Fe{sub 2}O{sub 3} hierarchical structures was proposed. Good photocatalytic properties were observed for all the hierarchical structures. - Graphical abstract: A dual iron precursors system in a hydrothermal process was developed for controllable fabrication of various alpha-Fe{sub 2}O{sub 3} hierarchical structures. Micro-pines, snowflakes and bundles were successfully fabricated by simply tuning the total concentration of the two iron precursors and their molar ratio. A possible formation mechanism of these structures was proposed.