Dual Ferro‐/Piezo‐Electric Coupling in Two‐Dimensional [Bi ₂ O ₂ ]‐Based Layered Structures for Synergistic Harvesting of Mechanical and Solar Energy

ABSTRACT 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 [Bi 2 O 2 ]‐based layered compounds (BiOBr@Bi 5 Ti 3 FeO 15 ) 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@Bi 5 Ti 3 FeO 15 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.