Bifunctional black phosphorus: coupling with hematite for Z-scheme photocatalytic overall water splitting

Abstract

Z-Scheme photocatalytic overall water splitting based on an oxygen production photocatalyst (OPP) and a hydrogen production photocatalyst (HPP) provides a promising opportunity for the conversion of solar energy into chemical energy. Herein, a novel all solid-state 2D–2D Z-scheme photocatalytic system is designed and constructed by coupling black phosphorus nanosheets (2D BP) with α-Fe₂O₃ nanoplates. 2D BP is used as an HPP and solid-state charge transfer mediator to produce H₂ and accelerate charge transfer, while α-Fe₂O₃ serves as an OPP. The introduction of 2D BP as solid-state charge transfer mediator promotes the carrier transfer, thus simultaneously realizing efficient H₂ and O₂ evolution. The optimum O₂ and H₂ evolution rates on this Z-scheme system are approximately 0.29 and 0.59 μmol h⁻¹, respectively, under simulated visible light illumination without using sacrificial agents. This study suggests the significance of a solid charge transfer mediator to accelerate the migration and separation of interface charges, thus improving the photocatalytic overall water splitting performance.