Remarkably boosting catalytic performance of BaTiO3-based materials via phase boundary, band-structure and defect engineering

BaTiO 3 (BT)-based ferroelectrics are constrained in piezo-photocatalysis by limited polarization tunability at room temperature and their intrinsically high phase-transition temperature. Constructing a multiphase coexistence structure near phase boundaries can effectively lower the energy barrier for polarization rotation, enhance the dynamic piezoelectric response, and facilitate the separation of photogenerated carriers. In this work, a multiphase-regulation strategy is developed via synergistic A-/B-site co-doping to activate the catalytic performance of BT-based materials. A Sr 2+ and Zr 4+ co-doped Ba 0.8 Sr 0.2 Zr 0.15 Ti 0.85 O 3 (BSZ 0.15 T) catalyst was synthesized via a non-hydrolytic sol-gel (NHSG) method. The optimized composition exhibits rhombohedral-orthorhombic-tetragonal (R-O-T) multiphase coexistence at room temperature. This feature significantly enhances polarization rotation and the piezoelectric response, thereby improving the efficiency of charge-carrier separation and transport. Under simultaneous ultraviolet irradiation and ultrasonic excitation, BSZ 0.15 T achieves a degradation efficiency of 99.5% for RhB degradation, with a rate constant k of 9.554 × 10 −2 min −1 . Mechanistic investigations reveal that the enhanced performance arises from the synergistic effects of optimized band structure, strengthened built-in electric fields, and tailored oxygen vacancies. Specifically, Zr 4+ incorporation induces a downshift of the conduction band, thereby enhancing the electron reduction capability. This effectively facilitates the reduction of O 2 to generate superoxide radicals (• O 2 − ${\mathrm{O}}_2^{-}$ ). Meanwhile, the multiphase coexistence and abundant oxygen vacancies jointly accelerate charge migration and surface redox kinetics. This work provides a new perspective for enhancing the piezo-photocatalytic activity of BT-based materials through the synergistic phase-boundary and defect engineering.