Synergizing the internal electric field and ferroelectric polarization of the BiFeO3/ZnIn2S4 Z-scheme heterojunction for photocatalytic overall water splitting

Abstract

Coupling the internal electric field and ferroelectric polarization via the modulation of surface electronic structures to achieve high carrier separation and migration efficiency is attractive but challenging in solar-to-chemical energy conversion. Herein, we report that coating ultrathin ZnIn₂S₄ nanoflakes on BiFeO₃ polyhedron microparticles constructs a ferroelectric polarization and internal electric field enhanced Z-scheme heterojunction photocatalyst (BiFeO₃/ZnIn₂S₄). Benefiting from the efficient photogenerated carrier separation and migration processes triggered by powerful spontaneous polarization and internal electric field, respectively, the nanocomposites exhibit strong half-reaction activity over hydrogen and oxygen evolution. Importantly, the optimal nanohybrid photocatalyst (ZB-3) delivered superior photocatalytic overall water splitting activity (H₂: 87.3 μmol g⁻¹ h⁻¹, O₂: 42.3 μmol g⁻¹ h⁻¹) with an apparent quantum efficiency of 1.12% at 420 nm in pure water under visible light irradiation, the highest activity reported thus far for ferroelectric-based heterojunction photocatalysts. The novel strategy of synergizing internal electric field and ferroelectric polarization via hybridization has been proposed to boost the separation and transfer efficiency of photogenerated charges in ferroelectric materials.