Enhanced photocatalytic removal of tetracycline by ZnO/NiCo2O4 through the construction of a p-n heterojunction

A new ZnO/NiCo2O4 photocatalyst was synthesized to develop systems for removing pharmaceutical pollutants. Various properties of the synthesized nanocomposite such as crystal structure, morphology, optical activity, chemical composition, electrochemical functions, and energy band structure were investigated. The study on tetracycline removal showed that the catalytic activity of the ZnO/NiCo2O4 nanocomposite (0.0426 min−1) is significantly higher compared to ZnO and NiCo2O4 individually. Morphology images confirmed the creation of a heterojunction between rice-shaped ZnO and NiCo2O4 nanoparticles. In photoluminescence and electrochemical impedance analyses, the nanocomposite displayed the weakest signal among its components, suggesting effective control of recombination and charge carrier transfer. The combination of NiCo2O4 with ZnO resulted in increased light absorption in the visible spectrum, contributing to its photocatalytic performance. The energy band structure of ZnO and NiCo2O4 was examined, presenting a detailed explanation of the most likely mechanism for the improved photocatalytic activity.