Ablation time and laser fluence impacts on the composition, morphology and optical properties of copper oxide nanoparticles

Nanosecond Ce:Nd:YAG pulsed laser ablation (PLA) with 1064 nm wavelength laser and 10 ns pulse duration with various laser fluence and ablation time is used to ablate pure Cu target in water. UV, Raman, XRD, SEM, FESEM and TEM analysis indicated that the synthesized NPs are spherical, core-shell type with two crystalline phases, Cu and Cu2O, and a thin amorphous CuO phase on the surface. The obtained NPs were in two different mean sizes of 40 and 80 nm. The grain sizes of crystalline Cu and Cu2O were estimated for all the synthesized samples. A growth in the Cu2O crystallinity of the NPs with enhancing of laser fluence in the constant ablation time was observed. The energy band gap of the NPs calculated for all the synthesized samples with assistance of UV-visible spectra and indicated that the energy band gaps are various between 3 and 2.5 eV. During the constant laser fluence irradiation, a red shift was observed in the energy band gap as ablation time increased. The behaviour of the UV-visible spectra, X-ray diffraction, crystallite size, mean particle size and energy band gap of the samples were studied as a function of laser fluence and ablation time.