Nano-MnO2anchored on exfoliated MXene with exceptional and stable Fenton oxidation performance for organic micropollutants

Peroxymonosulfate (PMS) Fenton-like systems have emerged as promising alternatives to hydrogen peroxide (H2O2). Fenton systems are currently used in the industry owing to their highly efficient utilization rate of oxidizing agents and wide operating pH ranges. Heterogeneous Fenton-like catalysts are promising candidates in this regard. However, self-aggregation and generation of ambiguous reactive oxygen species greatly restrict their broad application in practical settings. Herein, a redox reaction between exfoliated MXene and KMnO4facilitates the in-situdeposition of MnO2nanoparticles on the surface of Ti-deficient vacancies of MXene (MXene/MnO2). Owing to the advantages of MXene with fast charge transfer and MnO2with strong PMS activation ability, the engineered MXene/MnO2@PVDF catalytic membrane exhibited enhanced activity and excellent long-term stability for various refractory organic pollutants. Experimental observations, combined with density functional theory calculations, revealed that the exposed Mn sites effectively promoted the generation of 1O2. Interestingly, the widespread pathway for the direct generation of 1O2viahigh-valent Mn-oxo phases has a high energy barrier (3.34 eV). In contrast, the pathway that uses the •OOH species as intermediates to produce 1O2is energetically more viable (1.84 eV). This work offers insights into the in-situengineering of transition metal-oxides on MXene-based membranes, facilitating their implementation in remediating micropollutant-contaminated environmental water.