Ultrahigh piezocatalytic performance based on the micron-scale BaTiO₃ single crystal sheets with {111} highly exposed polar facets

Piezocatalytic two-electron oxygen reduction to produce hydrogen peroxide (H₂O₂) is an emerging and green synthesis method. However, the low H₂O₂ yield of current piezocatalysts that results from their low piezocatalytic activity has been a long-standing challenge. Here, we have developed “capacitor-like” BaTiO₃ single-crystal microsheets with {111} highly exposed polar facets, which are distinctively different from previously reported BaTiO₃ piezocatalysts. The pure single-crystal microsheets exhibit a significantly improved H₂O₂ yield of 521 μmol g⁻¹ h⁻¹ compared to conventional BaTiO₃ piezocatalysts. Remarkably, the yield significantly increases to 1088 μmol g⁻¹ h⁻¹ after photodeposition of Ag quantum dots onto the microsheets, which also exhibit a high degradation rate (k) of 0.259 min⁻¹ for Rhodamine B (RhB), surpassing that of existed ABO₃-type piezocatalysts reported to date for the same conditions. The excellent piezocatalytic activity is due to the high piezoelectric response of {111} single-crystal microsheets and the ability of Ag quantum dots to provide a high carrier activity under a double electric field, thereby promoting O₂ adsorption for efficient 2e⁻ reduction for H₂O₂ production. This work provides a novel design strategy to enhance the H₂O₂ yield of piezocatalysts, and develops a new understanding of piezoelectric-driven catalytic mechanisms for energy and environmental applications.