Understanding the Role of Band Bending and Surface Coordination in Steering Piezocatalytic In Situ H2O2 Evolution Routes

Abstract Piezocatalytic H2O2 production, employing water and oxygen as the raw materials, is emerging as a promising and viable alternative for in situ H2O2 evolution. However, the understanding of the structure–activity relationship of piezocatalysts still poses challenges, and the key factor steering the H2O2 evolution pathway also remains ambiguous. Herein, two bismuth ferrite-based materials with different crystal structures, perovskite-type BiFeO3 and mullite-type Bi2Fe4O9, were prepared for a systematic comparison of their piezocatalytic activity and an in-depth investigation into the routes of H2O2 in situ production. As a result, BiFeO3 achieved a higher H2O2 production rate (252.86 μmol·L–1) than Bi2Fe4O9 (140.32 μmol·L–1) over 60 min in ambient aqueous conditions without any sacrificial agent. Mechanism analysis reveals that a higher piezocatalytic H2O2 yield of BiFeO3 arises from its stronger piezoelectric response and surface coordination mode of bridging hydroxyl groups. The piezoelectric-induced band bending made water oxidation thermodynamically feasible, and the bridging hydroxyl groups offered hole-transfer channels, thereby collectively triggering the simultaneous occurrence of oxygen reduction reaction (ORR) and water oxidation reaction (WOR). This work provides fundamental insights into the crystal-structure-dependent piezocatalytic activity, offering a profound understanding of the mechanism underlying H2O2 evolution routes.