Bifunctional Photoelectrode Driven by Charged Domain Walls in Ferroelectric Bi₂WO₆

Photoelectrochemical technology provides a promising way to solve the emerging energy crisis, yet it still faces obstacles like weak charge transfer and separation of traditional photoelectrodes. Here, by using single crystalline epitaxial ferroelectric Bi₂WO₆ thin films, a bifunctional photoelectrode for photoelectrochemical water splitting is demonstrated, which originates from the in-plane ferroelectricity and charged domain walls. The optimized anodic (cathodic) photocurrent density is 0.175 (0.240) mA cm^-2 at 1.23 V (0 V) vs RHE in Na₂SO₄ (pH = 7) electrolyte solution. Manipulations of the in-plane polarization and charged domain walls provide an alternative catalyzing strategy toward efficient and controllable photoelectrochemical water splitting.