Excitation-wavelength-dependent photoluminescence/electrical conductivity of copper oxide nanorods

This research work reports the synthesis of copper (II) oxide (CuO) nanoparticles using the wet chemical co-precipitation method. The synthesised nanoparticles were characterised using ultraviolet–visible spectroscopy, X-ray diffraction, field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy in terms of absorption, crystal structure and size, morphology and elemental composition, and particle size. The existence of functional groups was verified by Fourier transform infrared spectroscopy. The synthesised copper (II) oxide nanoparticles showed an absorption peak at 397 nm, and a Tauc’s plot study showed a band-gap energy of 3.2 eV. The effects of varied excitation energies – namely, 3.81 and 3.54 eV – on the emission spectra of rod-shaped nanoparticles were assessed through photoluminescence spectroscopy, and the release of red, orange, green, violet and yellow colours was observed. The voltage–current characteristics of nanoparticle pellets were measured using a two-probe technique. The increase in the direct-current electrical conductivity of pellets heated at 100 and 200°C was ascertained. Overall, this research work provides valuable insights into the electronic properties of copper (II) oxide nanoparticles, which could have potential applications in various fields such as catalysis and electronics.