Defect and Interface Co‐Regulation Enabled Piezoelectricity Activation in SnSe ₂ for High‐Performance Piezo‐Photocatalytic H ₂ O ₂ Generation and Uranium Extraction

ABSTRACT The centrosymmetric crystal structure of SnSe 2 intrinsically excludes a piezoelectric property. Herein, a piezoelectric effect of SnSe 2 is activated via introducing Se vacancies (SnSe 2 ‐V Se ), endowing a piezoelectric coefficient as high as 19.9 pm V −1 . By leveraging the continuous anionic framework, the valence state compatibility, and the comparable atomic radii between Se and S, an atomically precise S‐scheme SnSe 2 ‐V Se @In 2 S 3 heterojunction is constructed. Systematic studies demonstrate that the Se vacancies generate strong localized polarization fields, which, in conjunction with the interfacial built‐in electric field (IEF) in SnSe 2 ‐V Se @In 2 S 3 , significantly enhance the carrier separation efficiency by 16‐fold as compared to pristine SnSe 2 ‐V Se . Theoretical calculations reveal that interfacial electronic coupling facilitates O 2 adsorption, while an upward shift in the Sn d‐band center optimizes the adsorption free energy of * OOH intermediates. Under the piezo‐photocatalysis, the system achieves an H 2 O 2 generation rate of 2.38 mmol g −1 h −1 through the oxygen reduction pathway, alongside enhanced O 2 evolution via water oxidation. Further, in‐situ generated H 2 O 2 mediates efficient U(VI) reduction and precipitation, enabling almost 100% uranium extraction from both simulated wastewater and artificial seawater.