Fabrication of Z-scheme g-C3N4/RGO/Bi2WO6 photocatalyst with enhanced visible-light photocatalytic activity

• Z-scheme g-C3N4/RGO/Bi2WO6 composite photocatalyst were obtained.
• The composite has much higher photocatalytic activity than that of pure ones.
• High dechlorination of TCP is due to the high reduction ability in CB of g-C3N4.
• Z-scheme composite could efficiently reduce the recombination of e−–h+ pairs.

An efficient visible-light-driven Z-scheme g-C3N4/RGO/Bi2WO6 composite was fabricated by the hydrothermal method. The prepared g-C3N4/RGO/Bi2WO6 composite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen sorption, Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectrometer (XPS). The photocatalytic activity of the g-C3N4/RGO/Bi2WO6 composite was evaluated by the degradation of 2,4,6-trichlorophenol (TCP) under visible-light irradiation. The photochemical test and scavenging experiment showed the photogenerated electrons (e−) and holes (h+) had strong reducing capability and oxidation capability, respectively. The photocatalytic activity of the g-C3N4/RGO/Bi2WO6 composite was higher than that of the pure g-C3N4, Bi2WO6, and g-C3N4/Bi2WO6 during the TCP degradation, which could be due to the efficient visible-light utilization efficiency and the construction of Z-scheme. RGO served as a charge transmission bridge between the g-C3N4 and the Bi2WO6, and the Z-scheme kept the electrons with high reducing capability in the conduction band (CB) of g-C3N4 and the holes with high oxidation capability in the valence band (VB) of Bi2WO6. The photogenerated holes of Bi2WO6 were the major active species in the TCP oxidative degradation, and the photogenerated electrons of g-C3N4 were the major active species in the TCP dechlorination.

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