Dual internal electric field synergistic interface and surface modification enhance photoelectrochemical performance of hematite photoanodes

Abstract

The efficiency of photoelectrochemical (PEC) water splitting using hematite (α-Fe₂O₃) photoanodes is often limited by poor charge separation and transport. In this study, an innovative multilayer photoanode architecture with a dual internal electric field (IEF) synergistic interface and surface modification was developed to enhance charge transport and separation efficiency. The structure incorporates a ZnMgO (ZMO) layer, an FeS hole transport layer (HTL), and an FeCoNiOOH (FCN) co-catalyst. Specifically, the ZMO layer, positioned between the FTO substrate and Ti-Fe₂O₃, forms a Z-scheme heterojunction that promotes internal charge separation. The FeS HTL and FCN co-catalyst were further incorporated onto the surface of the ZMO/Zn,Ti-Fe₂O₃ (ZMO/ZT-H) structure, thereby improving hole transport and modulating surface states. This integrated design resulted in a substantial improvement in PEC performance, achieving a photocurrent density of 4.57 mA cm⁻² at 1.23 V vs. RHE, with stable operation maintained over 40 hours. This work introduces novel strategies for interface and surface engineering that enhance carrier separation and charge transfer in Fe₂O₃-based photoanodes and offer valuable insights for advancing PEC water-splitting technologies.