Visible-light-driven photocatalytic degradation of ciprofloxacin by a ternary Mn2O3/Mn3O4/MnO2 valence state heterojunction

Valence state heterostructure exhibits great potential for contaminants remediation from water and wastewater with effective charge separation and little energy loss. However, the preparation process commonly shows complex with uncontrolled manner, forming undesired valence states, which hinders the advancement of valence state heterostructure. Herein, an Oxone induced strategy is established to controllably design manganese-based valence state heterostructure for the first time. A superior Mn2O3/Mn3O4/MnO2 (molar ratio of 3:1:2) photocatalyst with dual Ⅱ heterostructures was generated by Oxone (0.3 mM) induced Mn2O3 (0.2 g/L) under visible light. The Mn2O3/Mn3O4/MnO2 heterojunction achieved 95.6% removal and 63.9% mineralization of ciprofloxacin (cipro) under visible light irradiation for 40 min. The excellent catalytic performance was derived from the improved surface area, decreased isoelectric point, enhanced light absorption and efficient charge separation of the Mn2O3/Mn3O4/MnO2 heterostructure. Moreover, the radicals trapping experiment and Electron paramagnetic resonance (EPR) measurement revealed the dominant roles of holes and superoxide radicals for cipro degradation. Furthermore, the reusable Mn2O3/Mn3O4/MnO2 could remove cipro selectively with co-existing natural organic matters and inorganic ions, which exhibited high practicability in real waters. Impressively, this work provides an innovative approach for controllable design of valence state heterostructure and fabricates a promising photocatalyst towards antibiotics degradation.