Robust Coupling Between Piezoelectric Field and Interfacial Polarization in Layered Bismuth‐Based Heterostructure for High‐performance Piezocatalytic Water Splitting

The creation of heterostructures with inherent interface polarization has been proven effective in enhancing piezocatalytic activity; however, developing efficient heterostructure piezocatalysts remains challenging, and the underlying mechanisms are not well understood. In this work, a stable Bi₂WO₆/BiOBr heterostructure with strong chemical binding is successfully constructed by exchanging double Br^- with WO₄ ^2- in hydrothermal reaction. The heterostructure demonstrates exceptional piezocatalytic hydrogen evolution reaction (HER) efficiencies of 0.75 mmol g⁻¹ h⁻¹ in water and 2.28 mmol g⁻¹ h⁻¹ in methanol solution, respectively, outperforming the majority of recently reported bismuth-based piezocatalysts. During piezocatalytic operations, a robust coupling between the stress-induced piezoelectric field and the inherent interfacial polarization is pivotal. This coupling results in a large intrinsic dipole moment, excellent piezoelectricity, and improved carrier separation and transfer. Additionally, the polar surface of heterostructure facilitates decreased Gibbs free energy, increased surface potential, and reduced charge transfer resistance, all of which contribute to the high-activity surface piezocatalytic reaction. This study introduces a simple and universal method for in situ construction of layered bismuth-based heterostructures with high piezocatalytic performance and offers valuable insights into the role of polarization coupling in piezocatalysis.