Anion and Solvent Derived Morphology Controlling and Properties of β-FeOOH and α-Fe2O3

In this paper, α-Fe₂O₃ with different morphologies were controllable synthesized via a two-step route using NO₃- as a guiding agent. Environmentally friendly hydrothermal reaction was used to synthesize β-FeOOH with different morphologies. The concentration of sodium nitrate was adjusted to control the shapes and sizes of β-FeOOH. α-Fe₂O₃ is obtained via further calcination. By changing the concentration of sodium nitrate, the morphology could be tuned from nanoflowers which were composed by nanorods to single nanorod. The change of morphology is ascribed to the selective adsorption of NO₃- which lead to β-FeOOH to grow along the 〈001〉 direction. At the same time, an aqueous iron chloride was used as the precursor and the effect of ethanol as solvent on the morphology of α-Fe₂O₃ was investigated. Due to the selective adsorption of ethanol to the iron oxide crystal face, the morphology of α-Fe₂O₃ changes from the original sphere to the hexagonal nanosheet. Meanwhile, the electrochemical properties of iron oxide with different morphologies and the adsorption properties of Congo red were explored.