Vol. 7, Issue 1, Part C (2025)

Metal-oxide nanomaterials (MONMs) such as TiO₂, ZnO, and Fe₂O₃ have emerged as highly effective photocatalysts for environmental remediation due to their unique electronic, optical, and surface properties. This theoretical study explores the mechanistic aspects of pollutant degradation pathways mediated by MONMs, emphasizing the formation and dynamics of reactive oxygen species (ROS), charge carrier generation, and surface adsorption phenomena. Using density functional theory (DFT)-based insights from prior computational and experimental literature, we model the energy transitions, band-gap relationships, and adsorption energetics governing photocatalytic degradation of common organic pollutants such as phenol, dyes, and pharmaceuticals. The analysis identifies how dopant modification, surface functionalization, and nanostructural morphology modulate degradation efficiency. Theoretical models demonstrate that surface hydroxylation and defect engineering lower the activation energy for ROS generation, thereby enhancing pollutant oxidation kinetics. The study provides a consolidated framework for understanding the reaction pathways, offering directions for optimizing environmentally benign, scalable nanomaterials for pollution control.