Ferroelectric polarization engineering enables dual enhancement of interfacial electronic interaction and charge separation driving force in BaTiO3/CdS heterojunctions for photocatalytic hydrogen evolution

Simultaneously strengthening interfacial electronic interaction and charge-separation driving force remains a central challenge in photocatalytic heterojunction design. Herein, a chemically matched control platform is established by coupling CdS with ferroelectric tetragonal BaTiO 3 (T-BTO) and non-ferroelectric cubic BaTiO 3 (C-BTO), enabling direct identification of the ferroelectric contribution. Ferroelectric polarization in T-BTO promotes preferential Cd 2+ anchoring, more uniform CdS growth, and tighter interfacial contact, ultimately achieving stronger electronic coupling than in C-BTO/CdS. More importantly, the ferroelectric polarization field cooperates with the built-in electric field of the type-II heterojunction, thereby providing an enhanced driving force for charge separation and transfer. Consequently, T-BTO/CdS delivers a hydrogen evolution rate of 13.28 mmol g −1  h −1 under Xe lamp irradiation, outperforming pure CdS (0.95 mmol g −1  h −1 ) and C-BTO/CdS (5.23 mmol g −1  h −1 ) by factors of 13.9 and 2.5, respectively. This work identifies ferroelectric polarization engineering as an effective strategy for concurrently optimizing interface coupling and charge separation driving force in photocatalytic heterojunctions.