A versatile wet-chemical method for synthesis of one-dimensional ferric and other transition metal oxides

We developed a versatile method using alkylamines (octylamine and isobutylamine) as structure-directing agents for synthesis of various 1D transition metal oxides in aqueous solution. In this report, 1D iron and copper oxide precursors (for simplicity, we have denoted them as pre-Fe ₂O₃ and pre-CuO) and ZnO were prepared. After calcination and reduction, the 1D nanostructure of pre-Fe₂O₃ can be easily converted to 1D α-Fe₂O₃ and 1D Fe ₃O₄, successively. The aspect ratio of the 1D nanostructures increases with the reaction time. XRD, TEM, in situ TEM, and TGA were used to characterize the samples. Results showed that after calcination at temperatures higher than 300°C, the as-prepared 1D pre-Fe₂O ₃, which was polycrystalline, transformed into 1D single-crystalline α-Fe₂O₃. A mechanism of assembling and "packing" along a certain direction for the growth of the 1D nanostructure was confirmed.