Prominent role of oxygen vacancy for superoxide radical and hydroxyl radical formation to promote electro-Fenton like reaction by W-doped CeO2 composites

Abstract

The electro-Fenton like technology is one of the most promising methods for wastewater treatment. However, developing efficient and stable catalysts is still a long-term goal in practical applications. Herein, a series of W-doped CeO2 (W/CeO2) composites were obtained and used for the accelerated decomposition of ciprofloxacin. The results showed that 2% W/CeO2 composite presented excellent degradation ability under a wide range of pH value. The introduction of tungsten was beneficial for the formation of surface oxygen vacancies (OVs), which enhanced the adsorption and activation of oxygen gas. Scavenging studies and electron paramagnetic resonance (EPR) analysis indicated H2O2, O2– and OH were the main reactive species. Theoretical calculations based on density functional theory (DFT) proved that OVs on W/CeO2 composites surface worked as active sites, which could activate adsorbed O2 into O2– through one electron transferring and active H2O2 to OH. Finally, a convincing mechanism in degradation process was proposed.