The effect of growth parameters on the aspect ratio and number density of CuO nanorods

Abstract

We have studied how different growth conditions, namely, oxygen flow rate, annealing temperature and annealing time affect the diameter, aspect ratio and number density of CuO nanorods using scanning and transmission electron microscopy. CuO nanorods are synthesized by thermal annealing of thin copper foil. It is observed that while the diameter and number density of nanorods depend critically on the oxygen flow rate and annealing temperature, the aspect ratio and dispersion in diameter of nanorods can mostly be improved by thermal annealing for extended time periods. The growth mechanism of the nanorods is inferred from the evolution of observed microstructural changes. It is proposed that the growth of nanorods takes place from triangular shaped pyramids due to the relaxation of stress accumulated in oxide film during the process of oxidation and annealing.

Optical and magnetic properties of CuO nanowires grown by thermal oxidation

“…The previously reported CuO nanowires grown by oxidation have similar morphology and phase purity to that reported here. In addition, the presence of a low density of wires after oxidation at temperatures of 600 ºC and higher has been previously observed [14,15,21]. However, This agrees with the mechanism of Cu oxidation in air with a first step of Cu 2 O formation, which would correspond to the layer with large grains and lower oxygen content, followed by the formation of CuO, which correspond to the thin layer with small grains and the nanowires, as also supported by our XRD measurements.…”

“…In samples treated at higher temperatures, the nanostructures are wider and most of them have rod or ribbon shapes rather than the needle-like shape of the wires grown at 380 5 ºC. This is shown in the image of the structures grown after the 500 ºC annealing for 6 hours [14]. At moderate temperatures the Cu peaks from the substrate appear along with the peaks of the oxides while treatments at higher temperatures lead to a thicker oxide layer so that the patterns consist only of CuO and Cu 2 O peaks.…”

Surface Patterning of Functional Ceramics: A Materials Design

“…Whiskers and needles of cupric oxide at the nanoscale via oxidation have been reported (Kumar et al, 2004;Lin, 2004;Xu et al, 2004;Kaur et al, 2006;Fan et al, 2008). Oxidation-driven nanowire growth of TiO2 in an acetone saturated Ar environment and their applications in electro-emission and cell repellence have been reported in literature (Huo et al, 2008(Huo et al, , 2009Zhao et al, 2010).…”

Synthesis and Characterization of CuO Nanowires and Nanobelts

“…Although CuO nanostructures can be synthesized via chemical routes [1] nanowires of CuO have been produced by simply oxidizing Cu in air or oxygen environment [2][3]. The proposed oxidation process consists of two steps: first Cu is oxidized to Cu 2 O and then the CuO 2 is further oxidized to CuO [2].…”

“…The detailed growth processes of CuO nanowires by direct oxidation of Cu, however, are not completely understood. Two growth mechanisms have been proposed: vapor-solid growth process [2] and stress-induced growth process [3]. In this paper, we report study of the growth processes of CuO nanowires, their dependence on the experimental parameters and the unusual growth of large CuO nanobelts by direct thermal oxidation of various Cu substrates.…”