Ozonation is a widely used water treatment method that relies on the strong oxidative power of ozone to degrade organic pollutants. However, its practical application is limited by ozone's low solubility and selective reactivity toward certain compounds. To address these limitations, catalytic ozonation has been developed as an advanced redox technology (ART) that improves efficiency by facilitating ozone decomposition and enhancing hydroxyl radical (•OH) production. [1,2]. Spinel-type metal oxides are promising catalysts for this process due to their high thermal stability, rich surface oxygen vacancies, and flexible metal site occupancy. In this study, a ZnCo₂O₄ spinel catalyst was synthesized to utilize the redox-active nature of Co and the stabilizing role of Zn in the spinel structure. The synergistic interaction between Zn and Co was found to play a key role in promoting ozone decomposition and reactive radical generation. To further enhance the catalytic performance, the crystallinity of ZnCo₂O₄ was tuned via calcination temperature control. As crystallinity increased, the spinel structure became more ordered, which likely contributed to more stable cation distribution and coordination environments within the lattice. These structural changes are considered to support improved redox cycling of Co and enhanced generation of reactive oxygen species during ozonation. Among the tested catalysts, the sample calcined at 800 °C (denoted ZCO_800) showed the highest performance. XRD, FT-IR, SEM, and XPS confirmed progressive crystallization and favorable surface properties at this temperature. This work highlights how combining Zn–Co redox synergy, oxygen vacancy modulation, and crystallinity tuning can significantly enhance catalytic ozonation performance. These findings offer valuable insights for the rational design of efficient spinel-type catalysts for advanced water treatment applications. 

References 

  1. K. Ikehata and M. G. El-Din, Ozone Sci. Eng. 27, 83 (2005). 

2. M. S. Elovitz and U. von Gunten, Ozone Sci. Eng. 21, 239 (1999).