A Bifunctional Ferroelectric Catalyst Enabling Simultaneous Photoelectrochemical Water Oxidation and Two-Electron...

Photoelectrochemical (PEC) systems provide a sustainable approach to producing value-added chemicals by synergizing photo- and electrochemical processes. Beyond conventional strategies that focus on tuning intrinsic material properties, external field modulation emerges as a promising avenue for steering chemical reactions. Herein, a bifunctional ferroelectric catalyst Ba_0.7Sr_0.3TiO₃ (BSTO) is demonstrated on both photoanode and cathode to concurrently promote water oxidation and two-electron oxygen reduction reaction (2e^-ORR). BSTO-coated α-Fe₂O₃ is first selected as a model photoanode with enhanced PEC water oxidation performance upon controlled electric poling. Mechanistic studies indicate that ferroelectric polarization effectively tunes the band bending at the Fe₂O₃/BSTO interface, thereby facilitating charge separation. The general applicability of this strategy is further demonstrated with other metal oxide photoanodes, including TiO₂ and BiVO₄. On the cathode side, ferroelectric polarization induces a transition of the O₂ adsorption configuration from the Yeager- to the Pauling-type, which not only accelerates interfacial charge transfer kinetics but also favors the 2e^-ORR pathway, resulting in an increased H₂O₂ production rate. These findings highlight ferroelectric modulation as a versatile strategy for the design of high-performance (photo)electrocatalytic systems.