Influence of Pomegranate Peel-mediated Synthesis on the Physicochemical Characteristics and Photocatalytic Performance of CuO and TiO₂ Nanomaterials
J. Environ. Nanotechnol., Volume 15, No 3 (September 2026) pp. 201-214
Abstract
This study presents a detailed investigation of the physicochemical characteristics and photocatalytic performance of copper oxide and titanium dioxide nanoparticles prepared through conventional sol–gel and phytochemical-assisted routes. The chemically synthesized samples are denoted as (CuO)c and (TiO₂)c, while the biomediated products obtained using pomegranate peel extract are represented as (CuO)gs and (TiO₂)gs. X-ray diffraction analysis confirms the successful formation of monoclinic and tetragonal crystalline structures for the copper-based and titanium-based oxide nanomaterials, respectively. Incorporating plant-derived reducing and stabilizing agents does not significantly alter the lattice parameters. Fourier-transform infrared spectroscopy confirms the formation of metal–oxygen bonding networks and also indicates surface hydroxyl functionalities, which contribute to enhanced photocatalytic activity. Optical investigations reveal an increase in the band-gap energy of copper-based oxide from 1.89 eV to 2.58 eV after green synthesis, whereas a reduction in the band-gap energy from 3.02 eV to 2.82 eV is observed for titanium-based oxide. Photoluminescence measurements show predominantly blue emission for both copper- and titanium-based nanostructures, indicating radiative recombination involving band-edge and defect-related electronic states. The photocatalytic behavior of (CuO)c and (CuO)gs toward indigo carmine degradation under ultraviolet illumination was evaluated, yielding degradation efficiencies of 55% and 69%, respectively, after 180 min. Similarly, under identical irradiation conditions, removal of Congo red dye reached 93% for (TiO₂)c and 82% for (TiO₂)gs after 180 min. Scavenger-assisted experiments identified the active species involved in the degradation pathways of indigo carmine and Congo red. Furthermore, recyclability assessments over five consecutive cycles demonstrated the stability and reusability of the synthesized photocatalysts. The observed photocatalytic responses were interpreted based on the proposed charge-generation, migration, and reactive-radical formation mechanisms.
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