Tuning cobalt concentration in nickel oxide nanoparticles for enhanced photocatalytic degradation of selective textile dyes

Photocatalytic degradation is an eco-friendly method effective against a wide range of pollutants, including persistent textile dyes. In this study, cobalt-doped nickel oxide (NiO) nanoparticles were synthesized via a simple chemical precipitation method with varying Co concentrations (1-10 wt%). These nano catalysts were evaluated for the sunlight-assisted degradation of Methylene Blue (MB) and Rose Bengal (RB) dyes. Structural and morphological analyses were performed using SEM, TEM, XRD, FT-IR, and UV-Vis spectroscopy. Band gap values estimated from Tauc plots showed a significant reduction with Co doping, reaching a minimum of 2.76 eV at 3 % Co concentration. The incorporation of Co²⁺ ions into the NiO lattice induces asymmetric morphological evolution, enhancing both surface characteristics and photocatalytic degradation efficiency. The 3 % Co-doped NiO exhibits enhanced photocatalytic activity, achieving optimal degradation efficiencies of 77.8 % for methylene blue (MB) and 90 % for rho attributed to improved charge separation. EDX confirmed the successful incorporation of Co ions, which likely acted as electron acceptors or hole donors. Scavenger and cycling analyses confirmed the photocatalyst's efficiency and stability for environmental remediation.