Dual Ferro-/Piezo-Electric Coupling in Two-Dimensional [Bi₂O₂]-Based Layered Structures for Synergistic Harvesting of...

Piezoelectric-assisted photocatalytic systems, synergistically harnessing mechanical and solar energy, represent a promising frontier for energy conversion and environmental remediation. However, their practical implementation remains challenged by interfacial screening effects and inefficient carrier dynamics in conventional heterojunctions. Herein, we fabricated an inter-plane 2D/2D heterojunction of polar [Bi₂O₂]-based layered compounds (BiOBr@Bi₅Ti₃FeO₁₅) featuring matched electronic structures and dual piezoelectric response. This excellent structure facilitates the formation of interfacial chemical bonds (Bi-O-Ti and Bi-O-Fe bonds) and strong electronic interactions, which synergistically enhance piezoelectric and photoelectric properties by acting as charge transfer channels and strain-concentrated centers. Furthermore, under combined light illumination and ultrasonic vibration, a dual piezoelectric polarization field is established, which alternately breaks interfacial shielding effects while modulating interfacial band bending to achieve a Z-scheme charge transfer mechanism. This mechanism promotes photogenerated charge migration and redox kinetics, ultimately enabling full utilization of solar and mechanical energy. Consequently, the optimized BiOBr@Bi₅Ti₃FeO₁₅ achieved complete (100%) piezo-photocatalytic degradation of RhB (25 mg L^-1) within 6 min, exhibiting a degradation rate of 0.5399 min^-1, 1.76-fold and 128.5-fold higher than standalone photocatalysis (0.3057 min^-1) and piezocatalysis (0.0042 min^-1), respectively. This work provides a novel strategy for designing atomic-level 2D/2D ferro-/piezoelectric heterojunctions with tailored interfacial structures, effectively addressing the screening effect and weak interfacial interactions inherent to conventional piezoelectric heterojunctions, while advancing applications in energy and environmental technologies.