Hydrothermal synthesis of an artificial Z-scheme visible light photocatalytic system using reduced graphene oxide as the electron mediator

The electron mediator plays an important role in charge transfer in an artificial all-solid-state Z-scheme system. According to the energy band theory, a visible light photocatalytic system was designed by using reduced graphene oxide (RGO) as the electron mediator. The as-prepared g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was synthesized by hydrothermal process, and it was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen sorption , Raman spectroscopy , Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS) and diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was evaluated by analyzing the degradation of Rhodamine B (Rh B) under visible light irradiation. The photocatalytic degradation rate of Rh B for the g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was 8.73 and 5.19 times for the Bi 2 MoO 6 and g -C 3 N 4 /Bi 2 MoO 6 composite, respectively. The matched Fermi level structure provided the favorable interfacial charge transfer from the Bi 2 MoO 6 Photosystem II (PS II) to the g -C 3 N 4 Photosystem I (PS I) to promote the photocatalytic degradation of Rh B, suggesting that RGO was a suitable electron mediator in the Z-scheme system. The present study can provide a scientific basis for the rational design and realization of the Z-scheme system in environmental application.