Piezo-catalytic in-site H₂O₂ generation and activation across wide pH range to drive hydroxyl radical-mediated pollutant degradation.

Abstract

Hydroxyl radicals (·OH) is one of the most important reactive oxygen species (ROSs) for organic pollution controlling in advanced oxidation processes, while its production suffers from numerous H₂O₂ addition and narrow pH range in generally used Fenton reaction. Herein, we demonstrate a BiOIO₃ (BIO) piezo-catalyst loaded with γ-FeOOH nanoparticles (FNPs) (BF) that can convert O₂ to ·OH in a wide pH condition without external H₂O₂ addition under ultrasonication. It is found that the robust interfacial interaction facilitates rapid electron migration from BIO to FNPs, enabling two-electron O₂ reduction into H₂O₂ at the FNPs site, while the leaving behind piezo-holes to perform two-electron water oxidative H₂O₂ generation on BIO. Because the electron-rich nature of FNPs favors the H⁺ adsorption that contributes a surface acidic micro-environment, the produced H₂O₂ can be in-situ catalyzed into ·OH in either neutral or even alkaline conditions with a great stability. Finally, the optimal BF can achieve either an impressive ·OH yield of 38.1 µM h^-1 or a high H₂O₂ yield of 522.0 µM h^-1 by regulating the FNPs loading mass, which enables dual capabilities of rapid organic pollutants degradation and H₂O₂ production in a wide pH condition.