Study by Raman spectroscopy of anodization time effect on copper hydroxide nanorods

Abstract

Nanomaterials are currently of great interest to science and technology due to their physical, chemical, and mechanical properties can be adjusted according to their dimensionality, which is reflected in an improvement in their performance when compared to bulk or larger scale materials. Another advantage of nanomaterials is that can adopt different morphologies depending on the manufacturing method used. Nowadays there are different techniques for manufacturing nanomaterials. In this work, the anodization technique was used to obtain CuOH nanorods, because, compared to other techniques, anodization does not require expensive equipment or highly complex systems. To obtain CuOH nanorods, an electrolytic cell was used, formed by copper foils at 99.9 % purity, 0.3 mm caliber, and 3 cm2 of surface as anode. A 6 mm diameter cylindrical graphite rod as cathode and a solution of potassium hydroxide (KOH) with a concentration of 1.5 M as electrolyte also was used. A total of 21 samples were fabricated using times of 2 to 8 minutes, by 1-minute increments. Only a couple of samples were studied by scanning electron microscopy (SEM) to identify the morphology in anodized sheets and 7 samples were studied by Raman spectroscopy. The presence of nanorods composed of nanowires was corroborated by SEM, it was identified that nanorods have around 10 µm length and that the thicknesses are 200 nm and 50 nm respectively. By Raman microscopy was determined that nanorods are composed of CuOH, and a clear trend was found at the increase in the intensity of the Raman signals associated with CuOH as the anodization time increases. The reliability of use anodization technique for the manufacture of CuOH nanorods was demonstrated by means of the analysis carried out by Raman spectroscopy, since intensities in Raman signals associated with CuOH increase as the anodization time increases, strongly binding the thickness of the anodized layer with the anodizing time even though relatively short anodizing times (2-8 minutes) were used.