Efficient Catalytic Production of Reactive Oxygen Species through Piezoelectricity in Bismuth Sulfide Rich in Sulfur Vacancies.

Sulfur (S) vacancies in metal sulfides are of interest in electrocatalysis and photoelectronics, but their effect on the generation of reactive oxygen species (ROS) during mechanical catalysis is unclear. This study investigates the impact of S-vacancies in defective bismuth sulfide (BiS) on ROS production under ultrasonic irradiation and organic contaminant decomposition. S-vacancies disrupt the centrosymmetric structure of intrinsic BiS, inducing piezoelectric effects and enhancing the electrical energy in BiS. The positively charged S-vacancies in BiS promote the separation of ultrasound-activated electron-hole pairs by capturing electrons. As a result, the optimal rate of HO formation and the reaction rate constant for degrading Rhodamine B dye on BiS are found to be 1.9 and 37 times higher, respectively, than those on BiS under ultrasonic irradiation. The nonzero catalytic efficiency in centrosymmetric BiS is due to the flexoelectric catalytic effect from nonuniform strain. These results guide the piezocatalyst design and elucidate mechanical catalysis mechanisms.