Ba Doping Engineering in CaTiO ₃ : Tailoring Piezoelectric Response to Accelerate Photogenerated Charge Carrier Separation

ABSTRACT To address the prevalent issues of high photogenerated carrier recombination rates and low quantum efficiency in photocatalysts, this study for the first time adopts a simple BaCl 2 –CaCl 2 molten salt method. By regulating the doping levels of Ba(OH) 2 , Ba‐doped CaTiO 3 (BCT) nanorods are successfully synthesized while proposing a novel strategy that Ba doping breaks the central symmetry of CaTiO 3 to introduce piezoelectricity, thereby enhancing catalytic performance via piezoelectric–photocatalytic synergy. Experimental results confirm the prominent piezoelectric and reversible polarization properties of BCT, and the optimal Ba‐doped sample (BCT 1.5 ) demonstrates superior performance under ultrasonic‐light coupling conditions, achieving the photocurrent density of 2.34 mA/cm 2 (increasing 1.24‐fold compared to illumination‐alone condition) and minimum overpotential of 157.87 mV; also completely degrading methyl orange within 90 min. Furthermore, electrochemical and fluorescence spectroscopy investigations reveal that the piezoelectric built‐in electric field effectively promotes charge separation and suppresses recombination. Overall, this work provides a novel approach for developing high‐efficiency piezoelectric photocatalytic materials.