Controlled Growth of Large-Area, Uniform, Vertically Aligned Arrays of α-Fe₂O₃ Nanobelts and Nanowires

Abstract

Vertically aligned iron oxide nanobelt and nanowire arrays have been synthesized on a large-area surface by direct thermal oxidation of iron substrates under the flow of O(2). The effects of reactive gas pressure, composition, and temperature have been systematically studied. It was found that nanobelts (width, tens of nanometers; thickness, a few nanometers) are produced in the low-temperature region (approximately 700 degrees C) whereas cylindrical nanowires tens of nanometers thick are formed at relatively higher temperatures (approximately 800 degrees C). Both nanobelts and nanowires are mostly bicrystallites with a length of tens of micrometers which grow uniquely along the [110] direction. The growth habits of the nanobelts and nanowires in the two temperature regions indicate the role of growth rate anisotropy and surface energy in dictating the ultimate nanomorphologies.

Activation of Hematite Nanorod Arrays for Photoelectrochemical Water Splitting

“…Hematite nanorods and wires have been synthesized using chemical bath deposition (CBD) [12] and through the oxidation of iron foils. [13,14] Unfortunately, the photoelectrochemical (PEC)…”

Shape-controlled synthesis and cathodoluminescence properties of elongated α-Fe2O3 nanostructures

“…Surface diffusion mechanisms were proposed to account for the growth of ␣-Fe 2 O 3 nanoflakes, 23 bicrystalline hematite nanowires, 24 and aligned arrays of hematite nanowires as well. 11 In particular, the supply of iron atoms for ␣-Fe 2 O 3 nanowires growth has been considered to take place by surface diffusion along the sides of the nanowire and internal diffusion along planar defects up the axis of the nanowire. 11 Nevertheless, a mechanism involving VLS phase was also suggested for the growth of ␣-Fe 2 O 3 nanowires.…”

“…11 In particular, the supply of iron atoms for ␣-Fe 2 O 3 nanowires growth has been considered to take place by surface diffusion along the sides of the nanowire and internal diffusion along planar defects up the axis of the nanowire. 11 Nevertheless, a mechanism involving VLS phase was also suggested for the growth of ␣-Fe 2 O 3 nanowires. 25 Previous investiga- …”

“…Phys. 104, 124311 ͑2008͒ tion of ␣-Fe 2 O 3 nanobelts and nanowires 11 revealed that lowtemperature synthesis leads to the formation of nanobelts, while higher temperatures favor the growth of nanowires. No such observation is confirmed by our results.…”

“…9 In addition, several groups have synthesized nanowires of ␣-Fe 2 O 3 by oxidizing bulk iron in a mixed gas ambient. [10][11][12] However, the growth mechanism is still to be clearly determined. In addition, the optical properties of this oxide, especially luminescence properties, have been scarcely investigated.…”