Ferroelectric polarization promotes a CdS/In 2 Se 3 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/In 2 Se 3 , which enables the spontaneous overall water splitting reaction. The CdS/In 2 Se 3 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/In 2 Se 3 heterojunction promoted the charge transfer of CdS/In 2 Se 3 , 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/In 2 Se 3 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 In 2 Se 3 , respectively. Notably, the CdS/In 2 Se 3 -down configuration enables spontaneous photocatalytic water splitting in pH = 7, while the CdS/In 2 Se 3 -up configuration efficiently facilitates the HER process. This study highlights the significant advantages of CdS/In 2 Se 3 heterojunctions as photocatalytic materials, offering unique insights into the development and research of this promising heterojunction architecture.