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

Abstract

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.