Environmental sustainability is the cornerstone of the development of nanotechnology in today’s time. The synthesis of nanoparticles (NPs) based on green chemistry widely promotes this concept by minimizing the use of toxic precursors. Herein, the synthesis of titanium dioxide (TiO₂) NPs is reported using Origanum majorana extract. The mode of synthesis is facile, eco-friendly, economically, applicable, and rapid. The constituent phytochemicals of the extract responsible for the formation of the nanocatalysts were identified using FTIR spectroscopy. In addition, X-ray diffraction, particle size measurements, and transmission electron microscopy were used to characterize the nanocatalysts. Moreover, the ability of TiO₂ NPs to degrade rhodamine B dye under UV irradiation was also investigated. The key findings showed the marked photocatalytic property of the synthesized green TiO₂ NPs, which could be potentially incorporated as a nanoscale technique in the process of water purification for human use.

Nanomaterials have emerged as key platforms for environmental remediation owing to their tunable surface chemistry, high specific surface area, and multifunctional physicochemical properties. This review provides a critical comparison between conventional nanomaterials (CNMs) and phyto-mediated nanomaterials (PMNs), with particular emphasis on material design, surface chemistry, pollutant removal mechanisms, environmental performance, and sustainability. CNMs, including metal and metal oxide nanoparticles, carbon-based nanomaterials, and hybrid nanocomposites, offer excellent adsorption, photocatalytic, redox, and antimicrobial performance but remain constrained by concerns regarding toxicity, environmental persistence, and energy-intensive synthesis. PMNs provide a greener alternative by integrating plant-derived surface chemistry with nanomaterial functionality, potentially reducing reliance on hazardous synthesis reagents while modifying interfacial interactions relevant to environmental remediation. The review critically discusses the mechanistic roles of adsorption, surface complexation, photocatalytic degradation, electron-transfer processes, and reactive oxygen species (ROS) generation in pollutant removal. Recent advances in water purification, soil and groundwater remediation, carbon sequestration, and climate-related environmental applications are comprehensively summarized. Finally, current challenges associated with reproducibility, scalability, environmental safety, life-cycle assessment, and regulatory considerations are critically analyzed, together with future perspectives toward the rational design of sustainable nanomaterials for next-generation environmental remediation technologies.

Sunlight-assisted plant-mediated synthesis of silver nanoparticles (AgNPs) is well established, yet the complementary use of fluorescence spectroscopy to examine the optical response of complex phytochemical-containing media remains of interest. Here, Cucurbita pepo peel extract (CPE) was used for rapid AgNP formation under natural sunlight using single-step (A-Sun) and dropwise (B-Sun) addition strategies. The characteristic localized surface plasmon resonance (LSPR) band developed near 445–450 nm within 5 min, while corresponding dark controls showed negligible nanoparticle formation over the same period. Both dispersions retained their characteristic LSPR response during six months of optical monitoring. Steady-state photoluminescence (PL) measurements at excitation wavelengths of 300–350 nm and excitation–emission matrix (EEM) fluorescence mapping revealed lower recorded fluorescence intensities in the order CPE > A-Sun > B-Sun, with the principal emission region remaining broadly preserved near 435–440 nm. These observations provide complementary fluorescence fingerprints of the investigated preparations; however, inner-filter effects and light scattering may contribute to the measured attenuation, preventing its exclusive assignment to molecular quenching. FTIR revealed changes in oxygen-containing functional-group vibrations, while TEM showed predominantly spherical to quasi-spherical AgNPs, with mean particle diameters of 11.88 ± 3.60 nm for A-Sun and 9.77 ± 3.43 nm for B-Sun. The resulting dispersions also exhibited antibacterial activity against the six investigated bacterial strains. Overall, integrating PL and EEM with conventional characterization provides additional information on fluorescence changes accompanying sunlight-assisted AgNP formation without directly establishing the individual phytochemical reducing species, electron-transfer steps, or molecular surface-capping mechanisms.