Structural, electrical and optical properties of green synthesized ZnO nanoparticles using aqueous extract of thyme (Thymus vulgaris)

Production of nanoparticles (NPs) is an interesting research area due to the potential applications in the development of novel technologies. Especially, biologically produced nanomaterials have become an important branch of nanotechnology. In this study, two different zinc oxide (ZnO) samples were synthesised for comparison. The first one was produced using aqueous extract of thyme (Thymus vulgaris). The second sample was produced using Zn(Ac)₂·2H₂O solution in deionised water (dH₂O). The solutions which prepared in aqueous thyme extract and dH₂O were named as ZnO-1, and ZnO-2, respectively. The ZnO-NPs samples were characterised by X-ray diffraction (XRD) method. The XRD patterns of the both samples were indexed on basis of a hexagonal (wurtzite). Average crystallite sizes were calculated to be 42 and 85 nm for ZnO-1 and ZnO-2 samples, respectively. Morphological properties of the ZnO-NPs samples were determined with field emission-scanning electron microscopy and the grain sizes were measured to be 50 and 100 nm for ZnO-1 and ZnO-2 samples, respectively. Electrical conductivity measurements, carried out by the four point probe technique, showed that the ZnO-1 sample had higher electrical conductivity than the ZnO-2 sample. This suggests that the ZnO-1 sample has better crystal quality with lower defects along their length. In agreement, the ZnO-1 sample showed a higher transmittance (82–93%) in the UV–Vis range than the ZnO-2 sample.