Self-regulation of Lewis acid sites on FeOCl toward piezo-self-Fenton reaction for continuous hydroxyl radicals generation.

Abstract

Clarifying the structure-property relationship is critical to the design of high-performance piezocatalysts. Herein, with iron oxychloride (FeOCl) as the model piezocatalyst, a systematic investigation into the evolution of surface properties by the induced piezopotential is performed. Except for the promotion in carrier dynamics, the induced piezopotential also achieve in-situ regulation of the surface Lewis acid sites. The surface Lewis acidity of FeOCl, as well as other classic piezocatalyst such as BaTiO₃, BiTiO₃, and BiFeO₃, is dynamically enhanced under the application of mechanical stress. Consequently, the activation and consecutive conversion of the O₂ molecule, whose Lewis basicity is weaker than H₂O₂, is realized on the FeOCl piezocatalyst. The heterogeneous Fenton activity of FeOCl catalyst is upgraded into a more advanced piezo-self-Fenton activity, producing hydroxyl radicals efficiently under ultrasonic vibration (556.8 µmol g^-1 h^-1). The FeOCl piezo-self-Fenton system exhibits exceptional broad-spectrum degradation efficiency, operational stability, and scalability for the treatment of pharmaceutical wastewater. This work highlights the in-situ regulation of surface property by the induced piezopotential as a new feature for the piezocatalysts, which contributes to the enhancement of piezocatalytic activity and even changes the reaction pathway.