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.