Construction of Z-scheme photocatalytic systems using ZnIn2S4, CoOx-loaded Bi2MoO6 and reduced graphene oxide electron mediator and its efficient nonsacrificial water splitting under visible light

In this paper, a Z-scheme photocatalytic system was successfully constructed using ZnIn2S4 (ZIS), CoOx-loaded Bi2MoO6 (CoOx/BMO) and reduced graphene oxide (RGO) as H-2-evolving photocatalyst, O(2-)evolving photocatalyst and electron mediator, respectively. The material structures and chemical properties of the constructed Z-scheme photocatalyst were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity for water splitting over the Z-scheme photocatalytic systems has been investigated. The results indicated that they not only could steadily split water without any sacrificial agents injected under visible light irradiation, but also could achieve near stoichiometric amount of H-2 and O-2 for the constructed Z-scheme systems using RGO(3%)-CoOx/BMO as O-2-evolving photocatalyst. The amount of H-2 and O-2 can reach 740.4 mu mol.g(-1) and 376.7 mu mol.g(-1) in 24 h. The mechanism for photocatalytic water splitting has been discussed in detail. In addition, the Pt and CoOx cocatalysts were also the indispensable main factors as the H-2-evolving and O-2-evolving active sites in the Z-scheme photocatalytic water splitting system. (C) 2017 Elsevier B.V. All rights reserved.