Dual-electric field assisted efficient piezocatalytic synthesis of hydrogen peroxide with BiVO₄/Bi₂MoO₆...

Piezocatalysis, as an eco-friendly and sustainable strategy for hydrogen peroxide (H₂O₂) synthesis, enables efficient harvesting of ambient mechanical energy and utilization of ubiquitous water/oxygen resources. Nevertheless, its practical implementation faces severe challenges due to sluggish charge carrier migration kinetics. To address this limitation, herein a nanosheet-structured BiVO₄/Bi₂MoO₆ heterojunction was innovatively constructed via one-step hydrothermal method. Based on a series of experimental analysis and the density functional theory (DFT) calculations, an intimate type-II heterojunction between BiVO₄ and Bi₂MoO₆ was demonstrated, establishing robust interfacial electric field. Under ultrasound vibration, the optimized BiVO₄/Bi₂MoO₆ heterojunction demonstrated an exceptional H₂O₂ yield of 916.8 μmol·g^-1·h^-1 in pure water, which was 8.2 times and 6.9 times higher than pure BiVO₄ and Bi₂MoO₆, respectively, surpassing the majority of reported piezocatalysts. This outperformance was attributed to the coupling between the interfacial electric field and the induced piezoelectric polarization under mechanical stress, which not only endowed the heterojunction with stronger piezoelectric response as verified by the piezoresponse force microscopy (PFM) and piezoelectric nanogenerator (PENG) characterizations, but also facilitated charge carrier separation and transportation as supported by the electrochemical and photoluminescence results. In addition, the piezocatalytic H₂O₂ generation pathway with BiVO₄/Bi₂MoO₆ heterojunction was also investigated, and a two-step single-electron water oxidation reaction (WOR) dominated channel was proved. The dual-electric-field synergy strategy in this study is hoped to provide insights for the design of high-performance piezocatalysts towards H₂O₂ production and offer deep understandings to the development of mechanical-to-chemical energy conversion catalytic systems.