Bismuth-Vacancy-Tailored Lattice Distortion Activates Piezoelectric Polarization in Layered Sonosensitizers for...

Insufficient reactive oxygen species (ROS) generation by conventional sonosensitizers limits the efficacy of piezocatalytic tumor therapy. Here, a site-selective Bi-vacancy engineering strategy based on deep eutectic solvent (DES) etching is reported for Aurivillius-phase Bi₂WO₆ nanosheets (BWO), yielding Bi-deficient BXWO. Bi vacancies (V_Bi) increase the off-center displacement of W within the WO₆ octahedra and enhance local lattice asymmetry. The resulting octahedral distortion and vacancy-associated dipoles strengthen the built-in electric field (BIEF) and promote charge-carrier separation. Relative to pristine BWO, BXWO exhibits a 52% increase in the effective piezoelectric coefficient (d₃₃) and enhanced ROS generation under ultrasound stimulation. The amplified oxidative stress promotes lipid peroxidation and glutathione (GSH) depletion, consistent with ferroptotic tumor-cell death. These findings connect atomic-scale coordination distortion with macroscopic piezocatalytic performance and provide a site-selective defect-engineering strategy for sonosensitizer design.