A core–satellite structured Z-scheme catalyst Cd0.5Zn0.5S/BiVO4 for highly efficient and stable photocatalytic water splitting

Abstract

Fabrication of a Z-scheme photocatalytic system for hydrogen production and overall water splitting has huge potential in confronting the increasing worldwide energy crisis. But it is highly challenging to realize due to the harsh requirement for band edge levels and interfacial contact. Herein, we report the preparation of a high-efficiency and stable Z-scheme catalyst Cd_0.5Zn_0.5S–BiVO₄ with a core–satellite structure through the charge-induced assembly process in a mild water bath. A Cd_0.5Zn_0.5S–BiVO₄ Z-scheme junction shows an enormously enhanced photocatalytic activity for H₂ evolution under visible light illumination. The optimal photocatalytic H₂ evolution rate reaches 2.35 mmol g⁻¹ h⁻¹, which is 7.13 times higher than that of Cd_0.5Zn_0.5S, and an appreciable apparent quantum efficiency of 24.1% at λ = 420 nm was achieved. In particular, without any sacrificial donor, the Cd_0.5Zn_0.5S–BiVO₄ Z-scheme junction can overall split water into H₂ and O₂. The efficient photocatalytic activity of Cd_0.5Zn_0.5S–BiVO₄ is attributed to the formation of an intimate core–satellite structure and a Z-scheme photocatalytic mechanism, which not only greatly benefit the charge separation, but also prompt the photoinduced holes from Cd_0.5Zn_0.5S to rapidly recombine with the electrons of BiVO₄, hence reserving the most favorable reductive and oxidative reaction sites. Meanwhile, it inhibits the photocorrosion of Cd_0.5Zn_0.5S, guaranteeing the high photochemical stability (no activity decay after half a year). This work provides a new reference for the fabrication of a high-performance Z-schematic photocatalyst for water splitting.