Bi-Induced Structural Distortion Triggers Polarization Reinforcement and Enhanced Catalytic Degradation of Rhodamine B over BaTiO3

Bi-induced structural distortion was strategically engineered in BaTiO3 nanowires (BT NWs) to reinforce spontaneous polarization and achieve superior piezo-photocatalytic performance for efficient dye degradation. Bi-doped BT NWs (BT_xBi NWs) were synthesized via a facile two-step hydrothermal method. Comprehensive characterizations revealed that Bi3+ substitution at the A-site induces significant lattice contraction, surface cracks, polycrystalline characteristics, and an increased tetragonal phase fraction. These structural distortions, together with an enhanced carrier concentration and optimized electronic structure, markedly improve ferroelectric polarization, charge separation efficiency, and piezoelectric response under mechanical stress. Under ultrasonic-light synergistic conditions, the optimal BT_0.04Bi NWs exhibited an exceptional Rhodamine B (RhB) degradation rate constant of 487.3 × 10-3 min-1, which surpassed most reported piezo-photocatalysts. Reactive species trapping, electrochemical measurements, KPFM, DFT calculations, and COMSOL simulations collectively confirm that Bi doping breaks local symmetry, introduces additional polarization components, redistributes charge density, and amplifies local piezoelectric potential at crack sites. This work provides a novel and effective doping strategy for simultaneously modulating polarization and electronic properties in ferroelectric perovskites, offering new insights into the design of high-performance piezo-photocatalysts for environmental remediation.