Facile and low-cost synthesis of diverse copper oxide nanostructures for solar to thermal energy conversion

Abstract

Copper oxide (CuO) nanostructures were synthesized through a simple and low-cost wet chemical method using copper nitrate trihydrate as precursor and sodium hydroxide (NaOH) as stabilizing agent. Scanning electron microscopy analysis revealed formation of diverse CuO nanostructures as a consequence of varying the concentration of NaOH in the reaction medium. X-ray diffraction examination disclosed existence of end-centered monoclinic structured CuO as evident from the diffraction peaks observed at 2θ values corresponding to diffraction planes. Existence of cubic phase Cu2O was confirmed by presence of diffraction peak at 2θ value of 61.5°, corresponding to [0 2 2] diffraction plane. Energy-dispersive X-ray spectroscopy analysis proved pristine nature of the CuO nanostructures. UV-Vis-NIR reflectance value of CuO nanostructures prepared using different concentrations of NaOH exhibited reliable solar absorptance values, which were in accordance with their respective reflectance values. Among them, the CuO nanostructure prepared using NaOH concentration of 1.0 M disclosed high solar absorptance and selectivity values of 0.80 and 18.60, respectively.