Photocatalytic removal of eosin yellow dye in wastewater using silver-nickel oxide modified zinc oxide (Ag-NiO/ZnO) nanocomposite

The growing discharge of synthetic dyes from industrial sources poses significant threats to aquatic ecosystems and human health. Among these, eosin yellow is particularly persistent and resistant to conventional treatment methods. In this study, a silver–nickel oxide-modified zinc oxide (Ag–NiO/ZnO) nanocomposite was synthesized via a simple one-pot hydrothermal method and evaluated for visible light-driven photocatalytic degradation of EY. Optical analysis using Tauc plots revealed a progressive narrowing of the band gap from 3.16 eV (ZnO) to 2.93 eV (NiO/ZnO) and 2.77 eV (Ag–NiO/ZnO), enabling enhanced visible light absorption. The Ag–NiO/ZnO photocatalyst achieved 95.0 ± 1.5 % degradation of EY within 60 min, with a pseudo-first-order rate constant of 1.6 × 10⁻² min⁻¹ , significantly outperforming pristine ZnO and NiO/ZnO. Enhanced activity is attributed to improved light harvesting, efficient charge separation via p–n heterojunctions, and plasmonic effects of Ag nanoparticles. Radical scavenger tests confirmed the dominance of hydroxyl and superoxide species in the degradation mechanism. These findings position Ag–NiO/ZnO as a cost-effective and scalable material for visible-light-assisted photocatalytic wastewater treatment. • Ag–NiO/ZnO nanocomposite synthesized via one-pot hydrothermal method. • Band gap narrowed from 3.16 eV (ZnO) to 2.77 eV (Ag–NiO/ZnO). • Achieved 95 % EY degradation with a rate constant of 0.016 min⁻¹. • Visible light absorption enhanced by Ag SPR and NiO heterojunctions. • •OH and •O₂⁻ radicals identified as dominant active species.