Cooperation of oxygen vacancy and FeIII/FeII sites in H2-reduced Fe-MIL-101 for enhanced Fenton-like degradation of organic pollutants

Abstract

Metal-organic frameworks (MOFs)-based Fenton-like catalysts with mixed-valence and oxygen vacancies (OVs) were designed by H2 reduction of Fe-MIL-101 to activate H2O2. The degradation efficiency of norfloxacin (NOR) by Fe-MIL-101 treated at 220 °C (Fe-MIL-101-H-220) (100 %) was significantly higher than that of original Fe-MIL-101 (51.1 %) and showed excellent degradation efficiency for other pollutants. Moreover, the Fe-MIL-101-H-220/H2O2 system exhibited superior degradation efficiency for NOR over a wide pH range and could maintain 93.6 % after 5 cycles. The high performance is assigned to the cooperation of OVs and FeIII/FeII sites·H2O2 could be rapidly activated to produce •OH at the FeII sites. Further, electron-rich OVs sites could increase the interaction between adjacent FeIII sites and H2O2, benefitting the reduction of FeIII site to FeII site and accelerating FeIII/FeII cycle. This study provides a new strategy for the enhanced Fenton-like degradation of pollutants using iron-based MOFs catalyst, and unveils the intrinsic origin of the superior activity of thermally reduced Fe-MIL-101 for H2O2 activation.