Dual-Microsite Covalent Organic Framework-Functionalized Barium Titanate for Promoting Piezo-Catalytic Dual-Pathway...

Piezo-catalytic synthesis of hydrogen peroxide (H₂O₂) from air and pure water represents a highly promising production strategy. However, its rapid development is severely hindered by challenges in the catalytic process, such as weak substrate adsorption selectivity, poor charge separation and transfer efficiency, and limited reaction pathways. Herein, we present a piezo-catalyst composed of barium titanate in situ encapsulated by a covalent organic framework (COF/BaTiO₃), which enables the simultaneous conversion of water and oxygen into H₂O₂ under ultrasonic irradiation via dual micro sites, without requiring sacrificial agents or additional oxygen sources. Theoretical calculations and experimental results collectively demonstrate that the dual micro sites of COF/BaTiO₃ facilitate the directional preferential adsorption and activation of water and oxygen. Benefiting from the strong built-in polarization field formed by the overall enhanced piezoelectric response, electrons and holes are rapidly separated and directionally transported to the microsites. This enables a synergistic pathway dominated by two-electron water oxidation and supplemented by two-electron oxygen reduction on the dual micro sites, while suppressing the four-electron water oxidation reaction to achieve an impressive H₂O₂ yield of 240.7 µmol g^-1 h^-1. This work provides new insights for the design and development of piezo-catalysts for efficient overall piezo-catalytic H₂O₂ production.