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.