Synthesis of metal oxide nanoparticles by facile thermal decomposition of new Co(II), Ni(II), and Zn(II) Schiff base complexes- optical properties and photocatalytic degradation of methylene blue dye

Three new Co(II), Ni(II), and Zn(II) complexes of tridentate ONN ligand were synthesized from the reaction of 2-amino-3-hydroxypyridine and pyrole-2-carboxyaldehyde and characterized using physio-chemical and analytical methods such as NMR, elemental analyzer, FT-IR, ESI-MS, and magnetic moment measurement. The collected data indicated that prepared complexes have metal:ligand ratio of 1:1 and octahedral geometry for Co(II) and Ni (II) while tetrahedral geometry for Zn(II) complex. The synthesized complexes are utilized as precursors for synthesizing Co3O4, NiO, and ZnO NPs by thermal decomposition at 600 degrees C, and their structures were defined by PXRD, SEM, UV-DRS, FT-IR, and EDAX. By using Scherrer equation, the average crystallite size calculated for Co3O4, NiO, and ZnO nanoparticles are 22, 18, and 24 nm, respectively. The energy band gap of Co3O4, NiO, and ZnO nanoparticles are 1.67, 3.34, and 3.12 eV, respectively, according to the Tauc baseline calculation, revealing their semiconducting nature. Co3O4, NiO, and ZnO nanoparticles were employed for photocatalytic degradation of methylene blue dye in sunlight. After 105 min., the maximum percentage of MB dye degradation for Co3O4, NiO, and ZnO was found to be 80 %, 81.2 %, and 86.68 %, respectively.