NiO and Co-Doped NiO Multifunctional Nanomaterials: Biogenic Fabrication for Enhanced Photocatalytic Activity

Biogenically synthesized NiO and Co-doped NiO nanoparticles were fabricated using Rosella fruit extract as a natural reducing and capping agent. Structural analysis confirmed a cubic lattice with successful Co incorporation, resulting in a reduction of crystallite size from 10.73 nm to 8.93 nm and an increase in dislocation density. SEM imaging revealed agglomerated cubic morphologies, while EDS certified the elemental purity of Ni, O, and Co. UV-Visible spectroscopy showed a red-shifted absorption edge and band gap narrowing from 3.15 eV to 2.72 eV, favoring electron excitation. FTIR spectra confirmed the presence of metal-oxygen bonding and functional groups associated with the extract. Photocatalytic testing demonstrated the enhanced performance of Co-NiO, with 95.58% degradation of methylene blue, correlating with structural refinement and optical band tailoring. These findings demonstrate the effectiveness of Co substitution in modulating the microstructure and optoelectronic properties of NiO nanoparticles for advanced photocatalytic applications.