Ferroelectric polarization promotes a CdS/In₂Se₃ heterostructure for photocatalytic water splitting

The rapid recombination of photogenerated electrons and holes greatly limits the efficiency of photocatalyst based on semiconductor. In order to address this issue, we predicted a novel ferroelectric polarized heterojunction photocatalyst, CdS/In₂Se₃, which enables the spontaneous overall water splitting reaction. The CdS/In₂Se₃ heterojunction exhibits a band-edge staggered alignment and it is easy to form a direct Z-scheme charge transfer pathway. Besides, the built-in electric field (E_int) in the CdS/In₂Se₃ heterojunction promoted the charge transfer of CdS/In₂Se₃, leading to an improved separating efficiency of photo-generated carriers. Moreover, the vertical intrinsic polarized electric field (E_p) not only alters the position of the band edge but also reduces the bandgap limitations commonly associated with photocatalytic materials. Furthermore, the CdS/In₂Se₃ heterojunctions demonstrate separate catalytic activity for the hydrogen evolution reaction (HER) on the surface of the CdS monolayer and oxygen evolution reaction (OER) on the surface of In₂Se₃, respectively. Notably, the CdS/In₂Se₃-down configuration enables spontaneous photocatalytic water splitting in pH = 7, while the CdS/In₂Se₃-up configuration efficiently facilitates the HER process. This study highlights the significant advantages of CdS/In₂Se₃ heterojunctions as photocatalytic materials, offering unique insights into the development and research of this promising heterojunction architecture.