Efficient Fenton-like Process for Pollutant Removal in Electron-Rich/Poor Reaction Sites Induced by Surface Oxygen Vacancy over Cobalt–Zinc Oxides

To achieve high efficiency and low consumption for water treatment in the Fenton reaction, we use the surface oxygen vacancies (OVs) as the electron temporary residences to construct a dual-reaction-center (RDC) Fenton-like catalyst with abundant surface electron-rich/poor areas consisting of OV-rich Co-ZnO microparticles (OV-CoZnO MPs). The lattice-doping of Co into ZnO wurtzite results in the formation of OVs with unpaired electrons (electron-rich OVs) and electron-deficient Co³⁺ sites according to the structural and electronic characterizations. Both experimental and theoretical calculations prove that the electron-rich OVs are responsible for the capture and reduction of H₂O₂ to generate hydroxyl radicals, which quickly degrades pollutants, while a large amount of pollutants are adsorbed at the electron-deficient Co³⁺ sites and act as electron donors for the system, accompanied by their own oxidative degradation. The electrons obtained from the pollutants in the electron-deficient sites are transferred to the OVs through the internal bond bridge to achieve the balance of electron gain/loss. Through this process, pollutants are efficiently converted and degraded by multiple pathways in a wide range of pH (4.5-9.5). The reaction rate of the OV-CoZnO MPs/H₂O₂ system is increased by ∼17 times compared with the non-DRC system. This discovery provides a sustainable strategy for pollutant utilization, which shows new implications for solving the troublesome issues of the Fenton reaction and for developing novel environmental remediation technologies.