Rapid Catalyst-Free Flame Synthesis of Dense, Aligned α-Fe₂O₃ Nanoflake and CuO Nanoneedle Arrays

Abstract

This paper describes a simple and yet rapid flame synthesis method to produce one-dimensional metal oxide nanostructures by directly oxidizing metals in the postflame region of a flat flame. Single and bicrystal alpha-Fe(2)O(3) nanoflakes and CuO nanoneedles were grown in the postflame region by a solid diffusion mechanism and were aligned perpendicularly to the substrate with a surface coverage density of 10 nanostructures per square micrometer. The alpha-Fe(2)O(3) nanoflakes reached lengths exceeding 20 microm after only 20 min of growth. This rapid growth rate is attributed to a large initial heating rate of the metal substrate in the flame and to the presence of water vapor and carbon dioxide in the gas phase that together generate thin and porous oxide layers that greatly enhance the diffusion of the deficient metal to the nanostructure growth site and enable growth at higher temperatures than previously demonstrated.

Photoelectrode for water splitting: Materials, fabrication and characterization

“…Flame annealing method is reported by Zheng's group [87][88][89][90]. The as-deposited TiO 2 nanotube, Fe 2 O 3 nanorod, and so on undergo a fast annealing treatment to realize high crystallinity [87,90].…”

In-situ preparation of Fe2O3 hierarchical arrays on stainless steel substrate for high efficient catalysis

“…Currently, immobilization of Fe 2 O 3 micro/nanostructures has been reported on various substrates, including Fe foil [18][19][20], Ni foam [21], Ti foil [22], FTO [23] and stainless-steel [24,25]. Chemical bath deposition method was basically adopted to fabricate Fe 2 O 3 arrays on these substrates, which acted merely as supports for the material deposition [24,25].…”

Flame Aerosol Synthesis of Freestanding ZnO Nanorods

“…The technique is a non-continuous surface technique, and the use of a substrate limits its production capacity of the ZnOnanorods [14]. In a similar process, Rao and Zheng produced iron and copper oxide nanostructures in a flat flame by oxidizing a metal surface [18]. Most recently, iron oxide nanorods and MoO 2 nanowires were grown in CDF flames by Merchan-Merchan et al [19,20] by inserting their respective metal plates into the flames.…”