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

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. This study develops a piezocatalytic system based on BiOIO3/γ-FeOOH, which enables conversion of O2 to H2O2 and subsequent activation to ·OH for degradation of pollutants across a wide pH range (3-11) without the need for external H2O2 addition.