LAUSR

Ferroelectric materials are considered as promising photocatalysts due to their efficient charge separation via a polarization‐induced built‐in electric field. However, the polydomain structures hinder spatial charge separation and transfer due to the cancellation of polarization vectors in the domains. In this work, taking BiFeO3 (BFO) as a prototype, single‐domain BFO nanosheets with visible‐light absorption are prepared, as evident by piezoresponse force microscopy (PFM), spatially resolved surface photovoltage spectroscopy (SRSPS), and photodeposition experiments. The single‐domain BFO nanosheets show nine times activity in photocatalytic water oxidation reaction under visible‐light irradiation, compared with that of the polydomain BFO particles. With the asymmetric driving force for charge separation in a single domain, selective deposition of cocatalysts further enhances the photocatalytic activity of single‐domain ferroelectric BFO nanosheets. These results demonstrate the role of the single‐domain structure in constructing the driving force of charge separation in ferroelectric photocatalysts. The fabrication of single‐domain structures in ferroelectric photocatalysts to achieve enhanced photocatalytic activity offers a path to efficiently utilize the photogenerated charges in solar energy conversion.