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.

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