Bismuth‐Vacancy‐Tailored Lattice Distortion Activates Piezoelectric Polarization in Layered Sonosensitizers for Ferroptosis‐Enhanced Sonodynamic Therapy

ABSTRACT

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 Bi ₂ WO ₆ nanosheets (BWO), yielding Bi‐deficient BXWO. Bi vacancies (V _Bi ) increase the off‐center displacement of W within the WO ₆ 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 ( d ₃₃ ) 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.