In-situ utilization of piezo-generated hydrogen peroxide for efficient p-chlorophenol degradation by Fe loading bismuth vanadate

Piezocatalysis has emerged as a promising technology for environmental applications due to its capability to produce highly oxidative species by converting mechanical force into chemical energy. In this work, Fe-loaded bismuth vanadate (Fe/BVO) was developed as a catalyst for piezo-generation and in-situ utilization of hydrogen peroxide (H2O2). The piezoelectricity of Fe/BVO is confirmed by piezo-response force microscopy, and Fe displays a mixed valence (Fe(II) and Fe(III)). Fe/BVO piezocatalysis can achieve 86% p-CP degradation with ultrasonic treatment (120 W and 40 kHz) for 120 min, which is twice that of BVO piezocatalysis. While Fe loading decreases H2O2 concentration from 199.9 to 67.3 μmol/L due to the enhanced in-situ H2O2 utilization efficiency. Based on Mott-Schottky tests, Fe loading increases the charge carrier density, and accordingly leads to the improved piezocatalytic activity for H2O2 production and activation. In the Fe/BVO piezocatalytic system, H2O2 is generated by oxygen reduction via piezo-induced electrons and activated though Fe(II)/Fe(III) cycles. Meanwhile, quenching and fluorescence tests confirm that OH serve as the main active species for p-CP removal. This study is expected to provide a further understanding on the mechanism of piezo-Fenton processes and give some new insights for the design of piezocatalysts for in-situ H2O2 utilization.