Comparative Green and Wet-chemical Synthesis of ZnO Nanoparticles: Enhanced Photocatalytic and SERS Performance of Defect-rich Nanostructures
J. Environ. Nanotechnol., Volume 15, No 2 (June 2026) pp. 162-175
Abstract
Traditional chemical preparation of zinc oxide nanoparticles (ZnO NPs) is characterized by unsafe reagents, and small biomedical sensing and regenerative capacity. In an attempt to overcome these drawbacks, ZnO nanoparticles have been prepared by a conventional wet-chemical technique and green synthesis using Moringa oleifera leaves extract, Terminalia chebula fruit extract and Aloe vera gel extract. Optimized temperatures (400 - 700℃) were determined by thermogravimetric analysis and used to Calcine the synthesized nanoparticles and assess their structural, morphological, and optical characteristics by XRD, SEM-EDS, DLS, UV-Vis, ATR-FTIR, Raman spectroscopy, and SAED. XRD and UV-Vis analysis revealed that ZnO is hexagonal with a crystallite size between 11.1 to 72.2 nm and a bandgap of 3.11 to 4.22 eV respectively, which showed size effects of quantum confinement. Investigations of photocatalytic studies under an irradiation of 365 nm UV showed a high degradation efficiency of 67% methyl orange with Moringa-mediated ZnO in 180 min, which was higher than the degradation efficiency of 60% with Aloe vera, 35% with Terminalia chebula and 61%/32% with wet-synthesized samples at various calcination temperatures. Surface-enhanced Raman scattering (SERS) analysis of L-phenylalanine had an enhancement factor of the order of 10.2, which is due to defect-mediated charge-transfer processes. These findings confirm that green-synthesized ZnO nanoparticles are potential multifunctional materials in photocatalysis, SERS sensor detection, and bio-applications in bone regeneration systems.
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