Enhanced redox activity and oxygen vacancies of perovskite triggered by copper incorporation for the improvement of electro-Fenton activity

Abstract

ABO3 perovskite oxides doped with cation substitutions have been proved to change the inherent electronic and structural properties of perovskite. However, the role of perovskites substituted by B sites element in tailoring their electronic structure, crystal structure and surface chemical reaction on the degradation of organic pollutants by heterogeneous electro-Fenton (EF) process still remained obscure. Herein, the incorporation of Cu in LaCoO3 perovskite (LaCoxCu1−xO3−δ) was designed as heterogeneous EF catalyst for almost completely removal of target pollutant ciprofloxacin (CIP) within 120 min. The results showed that incorporation of Cu could effectively improve EF activity due to the enhancement of redox activity and oxygen vacancies (OVs) of LaCoxCu1−xO3−δ, which synergistically promoted the activation of hydrogen peroxide to hydroxyl radical (·OH). Furthermore, the superoxide free radical (O2−) was remarkably increased due to the electron-rich OVs and the redox pairs of Co2+/Co3+ and Cu+/Cu2+. Meanwhile, the pseudo-first order kinetic constant of the degradation process was investigated to evaluate the degradation effect of LaCoxCu1−xO3−δ. Finally, the degradation mechanism was investigated by EPR and scavenger experiments, which unraveled the important role of cation substitutions in perovskite oxides for the improvement of heterogeneous EF activity. The results provided insights into the incorporation strategy in perovskite oxides for improving heterogeneous EF activity in a rational approach.