Surface-modified ZnO nanoparticles for enhanced environmental and biomedical performance

Abstract

The present study explores the synthesis of cetyltrimethylammonium bromide -modified zinc oxide nanoparticles (CTAB: ZnO NPs) via a precipitation-cum-hydrothermal route, optimizing their multifunctional capabilities for photocatalytic dye degradation and antibacterial applications. The synthesized ZnO NPs exhibit a wurtzite hexagonal structure, as confirmed by X-ray diffraction (XRD), with an average crystallite size of 47.12 nm, refined through Williamson-Hall (107.8 nm) and modified Debye-Scherrer (41 nm) analyses to account for lattice strain effects. UV–visible spectroscopy reveals a sharp absorption peak at 430 nm, with a corresponding band gap of 3.2 eV, indicative of strong quantum confinement effects. High-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) confirm the quasi-spherical morphology with minimal agglomeration, while energy-dispersive X-ray spectroscopy (EDX) validates the purity of the ZnO composition. Photocatalytic investigations demonstrate a remarkable degradation efficiency of 100 % for reactive blue-81 (RB-81) dye under UV irradiation within 1.3 h, with a kinetic reaction rate of 5.71 × 10 2 μmol g⁻ 1 h⁻ 1 . Quantum yield (QY) and space-time yield (STY) values of 2.53 × 10⁻⁴ molecules photon⁻ 1 and 1.27 × 10⁻⁵ molecules photon⁻ 1 mg⁻ 1 , respectively, highlight the superior photonic utilization efficiency compared to conventional TiO₂-based photocatalysts. Antibacterial studies using the agar well diffusion method reveal significant inhibition zones of up to 3.42 cm and 2.14 cm for Staphylococcus aureus and Pseudomonas aeruginosa , respectively, demonstrating potent antibacterial activity. The findings indicate that CTAB: ZnO NPs not only enhance photocatalytic degradation and antibacterial efficacy but also offer scalable potential for environmental remediation and biomedical applications.