Ferroelectric-enhanced Photoelectrochemical Water Splitting: A Review of Recent Progress on the Mechanism.

Photoelectrochemical (PEC) water splitting is a top green tech for renewable energy, turning solar power into storable hydrogen. The efficiency of PEC water splitting is constrained by charge separation and surface reactions. While traditional material modifications like heterojunction design and defect regulation have enhanced efficiency, they are limited by material properties. The ferroelectric material provides a novel strategy to address these limitations in PEC water splitting. Ferroelectric materials, with their spontaneous polarization, can enhance charge separation and regulate surface reactions in PEC water splitting via internal electric fields. This paper summarizes the mechanism of ferroelectric polarization and its role in PEC, especially how ferroelectric polarization promotes bulk charge separation and surface reactions. It also reviews the research progress made in recent years regarding the enhancement of PEC performance through ferroelectric polarization. This includes applications in two main aspects: charge separation, which involves pure ferroelectrics, ferroelectric-semiconductor heterojunctions, and ferroelectric-plasmonic structures; and surface reactions, which cover electronic structure modification, pH regulation, and nanostructures. Studies have shown that ferroelectric polarization can significantly improve the charge separation efficiency and optimize the surface reaction kinetics by regulating the interfacial energy band structure. Finally, the future development of this promising research field is prospected.