Structure-tailored superlattice Bi7Ti4NbO21: Coupling octahedral tilting and rotation induced high ferroelectric polarization for efficient piezo-photocatalytic CO2 reduction

Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field, are highly promising piezo-photocatalytic candidate materials. In addition, developing structural design and revealing polarization enhancement in-depth mechanism are top priorities. Herein, we introduce the intergrowth ferroelectrics Bi 7 Ti 4 NbO 21 thin-layer nanosheets for piezo-photocatalytic CO 2 reduction. Density functional theory (DFT) calculations indicate that interlayer lattice mismatch leads to increased tilting and rotation angle of Ti/NbO 6 octahedra on perovskite-like layers, serving as the main reason for increased polarization. Furthermore, the tilting and rotation angle of the interlayer octahedron further increase under stress, suggesting a stronger driving force generated to facilitate charge carrier separation efficiency. Meanwhile, Bi 7 Ti 4 NbO 21 nanosheets provide abundant active sites to effectively adsorb CO 2 and acquire sensitive stress response, thereby presenting synergistically advanced piezo-photocatalytic CO 2 reduction activity with a high CO generation rate of 426.97 μmol g −1 h −1 . Our work offers new perspectives and directions for initiating and investigating the mechanisms of high-performance intergrowth piezo-photocatalysts. Intergrowth ferroelectric Bi 7 Ti 4 NbO 21 thin-layer nanosheets (BT-BTN-S), with strong ferroelectric polarization and excellent mechanical force sensitivity, are developed as piezo-photocatalyst for CO 2 reduction. The octahedron in BT-BTN exhibits self-tilting and self-rotation to adapt to lattice mismatch, resulting in stronger spontaneous polarization electric field. When ultrasonic vibration is applied, BT-BTN-S generates a super-strong piezoelectric polarization to facilitate charge carrier separation efficiency. • Mild synthesis of intergrowth Bi 7 Ti 4 NbO 21 with strong ferroelectric polarization • Synergistically piezo-photocatalysis for CO 2 reduction performance • Strong piezoelectric field promotes charge separation/transfer and conversion of CO 2