Enhancing charge transfer efficiency of cerium-iron oxides via Co regulated oxygen vacancies to boost peroxymonosulfate activation for tetracycline degradation

Enhancing the charge transfer efficiency and accelerating the redox cycle are effective approaches for improving the ability of catalysts to activate peroxymonosulfate (PMS). Herein, cobalt regulated cerium-iron oxides (CFOCo) were constructed successfully. Cobalt doping significantly reduces the particle size of cerium-iron oxides (CFO) and increases the concentration of oxygen vacancies, which further enhances the charge transfer efficiency and accelerates the redox cycle to generate more reactive oxygen species (ROS). Therefore, CFO-Co exhibits boosted PMS activation which could degrade 71.2% of tetracycline (TC) within 3 min and the rate constant can be up to 0.39 min 1, which is 5.6 times higher than that of pure CFO. In the meantime, CFO-Co still showed excellent catalytic performance under wide range of pH values, temperature, various polluted water bodies, coexisting ions, and long-term cycling conditions. Moreover, CFO-Co displayed easy catalysts recovery for its magnetic behavior. DFT calculation shows that the introduction of cobalt can significantly reduce the adsorption energy of PMS on the catalyst and lengthen peroxy bond (IO-O), which promotes the activation of PMS to produce ROS. The mechanism studies demonstrated that O-1(2), center dot OH, O-2(-)center dot and SO4- generated during the reaction were the main active species. The possible degradation pathways and the toxicity were also analyzed. This work offers a new view on the design of PMS-activated catalysts.