Green synthesis of ZnO nanoparticles using Cocos nucifera leaf extract: Characterization, antimicrobial, antioxidant, and photocatalytic activity

Zinc oxide nanoparticles (ZnO NPs) have been successfully prepared using
Cocos nucifera leaf extract and investigated with their antimicrobial,
antioxidant, and photocatalytic activity. The structural,
compositional, and morphological properties of the NPs were recorded and
studied systematically to confirm the synthesis. The aqueous suspension of
NPs showed a UV-Vis. absorption maxima of 370 nm indicating primarily its
formation. The XRD analysis identified the NPs with hexagonal wurtzite
structure with an average particle size of 16.6 nm. The FTIR analysis
identified some biomolecules and functional groups in the leaf extract as
responsible for the encapsulation and stabilization of ZnO NPs. The EDX
analysis showed the desired elemental compositions in the material. A
flower-shaped morphology of ZnO NPs was observed by SEM with a grain size
of around 15 nm. The optical properties of the NPs were studied by UV-Vis
spectroscopy and the bandgap was calculated as 3.37 eV. The Prepared ZnO
NPs have demonstrated antimicrobial activity against T. harzianum, and S.
aureus with a ZOI (zone of inhibition) of 14 and 10 mm, respectively. The
photocatalytic behavior of ZnO NPs showed absorbance degradation at around
640 nm and discolored methylene blue dye after one hour with a degradation
maximum of 84.29 %. Thus, the prepared ZnO NPs could be used potentially
in antibiotic development, pharmaceutical industries, and as
photocatalysts.