Self-cleaned surface of vanadium boride for long-lasting and boosted Fenton oxidation

Coupling extra electron supply with iron-mediated advanced oxidation processes (AOPs) is an efficient strategy for long-lasting oxidation of organic contaminants in environmental remediation. Many subsequent attempts have been made, such as homogeneous catalysts and metal catalysts, of which secondary organic pollution and surface passivation layers limit their application. In this work, metal borides as co-catalysts can efficiently accelerate the Fenton reaction by firmly sacrificing electrons to Fe(III) reduction. Among multiple metallic borides, vanadium boride (VB₂) performs superiorly as dual active sites to solve the Fe(III) cycle dilemma and quickly generate hydroxyl radicals via Fenton reaction for almost completely eliminating almost carbamazepine (CBZ) in VB₂/Fe(III)/H₂O₂. Characterization analysis and the density functional theory (DFT) calculation unveil that the synergistic effect of V and B on the surface of VB₂ makes Fe-O bonds of FeOH²⁺ weaker (from 173.8 pm to 178.4 pm) to produce more active Fe(III) species. And meanwhile, active Fe(III) can be rapidly reduced into Fe(II) on the surface of VB₂ and then be completely released into solution for subsequent Fenton reaction and hydroxyl radical generation. More importantly, VB₂ performs steadily and efficiently for 7th consecutive test in VB₂/Fe(III)/H₂O₂ to degrade more than 95% CBZ, resulting from the self-cleaning surface of VB₂ to expose reactive regions for persistent electron sacrifice and sustainably stimulative Fenton oxidation. Therefore, this research offers the detailed fundamental perception into the genesis of VB₂ as well as a novel electron donor for boosting Fenton oxidation towards water remediation.