Novel NiO nanoparticles via phytosynthesis method: Structural, morphological and optical properties

Nickel oxide nanoparticles (NiO NP) were successfully fabricated by phytosynthesis method using Ageratum conyzoides L leaf extracts (ACLE) in the various extract fractions such as water (NiO-W), methanol-water (NiO-MW) and n-hexane (NiO-Hx). Each extract fraction produced NiO NP with different structures, bandgap energies and morphologies due to the effect of calcination temperature during the phytosynthesis and biomolecules dissolved in each fraction. NiO NP was characterized by EDS and FTIR. Specifically, the structural, optical and morphological properties of NiO NP were confirmed by XRD, UV-Vis DRS and SEM, respectively. As a result, NiO-W, NiO-MW, NiO-Hx showed the morphologies of flakes-shaped, a porous foam-like and spherical, respectively. Meanwhile, various calcination temperatures caused the structural change of NiO NP. Additionally, the optical band gap of NiO-W, NiO-MW, and NiO-Hx were 3.77; 3.53 and 3.32 eV, respectively, by the increase of crystallite size to 20.47 nm; 23.09 nm and 23.43 nm, respectively.