TY - JOUR AU - Mfon, Rebecca Emmanuel AU - Hall, Simon R AU - Sarua, Andrei PY - 2020/01/31 Y2 - 2024/03/28 TI - Effect of Ocimum gratissimum plant leaf extract concentration and annealing temperature on the structure and optical properties of synthesized zinc oxide nanoparticles JF - EDUCATUM Journal of Science, Mathematics and Technology JA - EJSMT VL - 7 IS - 1 SE - Articles DO - 10.37134/ejsmt.vol7.1.1.2020 UR - https://ejournal.upsi.edu.my/index.php/EJSMT/article/view/3095 SP - 1-13 AB - <p style="text-align: justify;">Zinc oxide nanoparticles biosynthesized using two concentrations of <em>Ocimum gratissimum</em> (Og) plant leaf extracts were annealed at two different &nbsp;temperatures. Their UV-Vis absorbance peaks&nbsp; at 372 nm - 375 nm indicate a blue shift in excitonic absorption and &nbsp;their&nbsp; optical energy band gap values were in the range 3.22 eV – 3.31 eV. &nbsp;&nbsp;SEM images show the nanoparticles to be polydispersed and of a wide range of sizes with smaller nanoparticles clustering around bigger micrometer- sized ones with sharp edges. An annealing temperature of 400 &nbsp;resulted in the sintering of the nanoparticles but nanoparticles annealed at 250 &nbsp;&nbsp;had porous surfaces suggesting a possible use in gas sensor applications. XRD patterns show that the ZnO nanoparticles have the hexagonal wurtzite structure and are of good crystalline structure.&nbsp; Obtained crystallite sizes increased with annealing temperature and were in the range 14 nm to 29 nm. &nbsp;FTIR spectra show phenols, amines and aldehydes as the available reducing agents involved in the nanoparticle synthesis. The photoluminescence (PL) spectra show two emission peaks: a UV emission peak at 369 -381 nm indicating that the zinc oxide nanoparticles exhibited band-edge photoluminescence and a green emission peak at 523 nm – 538 nm suggesting the presence of defects from singly ionized oxygen vacancies. The PL peak intensities were dependent on the annealing temperatures with the UV- emission peaks for higher annealing temperatures exhibiting a spectral shift towards lower wavelengths.&nbsp; Plant leaf extracts concentration and the annealing temperatures used affect the structure and optical properties of the synthesized ZnO nanoparticles.</p><p>&nbsp;</p><p>&nbsp;</p> ER -