The topotactic transformation of lepidocrocite involves a Fe2+ adsorption process on the surface of the oxyhydroxide30–33 represented in reaction (8)33. (8) The subscripts specify the adsorption site and assuming one Fe2+ ion, in the hydrolysed form FeOH+, is adsorbed on the OH group of lepidocrocite and the other one on the The adsorption of Fe2+ ion is crucial for topotactic transformation of lepidocrocite and could help to explain the second source (apart from water reduction on the cathode) of OH- ions that is observed in Figure 1. When sufficient has been γ-FeOOH generated, direct Fe2+ adsorption on lepidocrocite may slow down the production of Fe(OH)2 due to increased competition for the ionic iron species. This, in turn, would cause an accumulation of OH- ions at the cathode, raising the pH to more alkaline values. The adsorbed intermediate undergoes a dissolution process and since both Fe3+ and Fe2+ are present, it transforms directly to magnetite. Reordering of the crystal structure can occur via a dehydration process; olation-oxolation allows cation rearrangement through the loose oxyhydroxide structure28,31. 3.5 The effect of dissolved oxygen on the electrochemical synthesis of magnetite.
The topotactic transformation of lepidocrocite involves a Fe2+ adsorption process on the surface of the oxyhydroxide30–33 represented in reaction (8)33. (8) The subscripts specify the adsorption site and assuming one Fe2+ ion, in the hydrolysed form FeOH+, is adsorbed on the OH group of lepidocrocite and the other one on the The adsorption of Fe2+ ion is crucial for topotactic transformation of lepidocrocite and could help to explain the second source (apart from water reduction on the cathode) of OH- ions that is observed in Figure 1. When sufficient γ-FeOOH has been generated, direct Fe2+ adsorption on lepidocrocite may slow down the production of Fe(OH)2 due to increased competition for the ionic iron species. This, in turn, would cause an accumulation of OH- ions at the cathode, raising the pH to more alkaline values. The adsorbed intermediate undergoes a dissolution process and since both Fe3+ and Fe2+ are present, it transforms directly to magnetite. Reordering of the crystal structure can occur via a dehydration process; olation-oxolation allows cation rearrangement through the loose oxyhydroxide structure28,31. 3.5 The effect of dissolved oxygen on the electrochemical synthesis of magnetite.
New_insights_into_the_electrochemical_formation_of_magnetite_nanoparticles.docx