Metal Borides as Excellent Co-Catalysts for Boosted and Long-Lasting Fenton-like Reaction: Dual Co-Catalytic Centers of Metal and Boron

The continuous electron supply for oxidant decomposition-inducedreactive oxygen species (ROS) generation is the main contributor forthe long-standing micropollutant oxidation in the iron-based advancedoxidation processes (AOPs). Herein, as a new class of co-catalysts,metal borides with dual active sites and preeminent conductive performancecan effectively overcome the inherent drawback of Fenton-like reactionsby steadily donating electrons to inactive Fe(III). Among the metalborides, tungsten boride (WB) exhibits a significant co-catalyticperformance run ahead of common heterogeneous co-catalysts and exceptionallyhigh stability. Based on qualitative and semi-quantitative tests,the hydroxyl radical, sulfate radical, and iron(IV)-oxo complex areall produced in the WB/Fe(III)/PDS system and Fe(IV)-induced methylphenyl sulfoxide decomposition is up to 72%. Moreover, the productionefficiency of ROS and relative proportions of radical and nonradicalpathways change with various experimental conditions (dosages of PDS,WB, and solution pH) and water matrices. The rate-determining stepof Fe(II) regeneration is greatly accelerated resulting from the synergeticeffect between exposed metallic reactive sites and nonmetallic boronwith reductive properties of WB. In addition, the self-dissolutionof surface tungsten oxide and boron oxide leads to a renovated surfacefor sustainable Fe(III) reduction in long-term operations. Our discoveryprovides an efficient and sustainable strategy in the field of enhancedAOPs for water remediation. Sufferingfrom low efficiency, secondary pollution introduction,and high cost of existing strategies, this work reported a class ofhigh-efficient, long-lasting, and eco-friendly co-catalysts to enhanceFenton-like oxidation for environmental remediation.