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Cross-Linked g-C3N4/rGO Nanocomposites with Tunable Band Structure and Enhanced Visible Light Photocatalytic Activity

Authors

  • Yibing Li,

    1. Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia
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  • Haimin Zhang,

    1. Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia
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  • Porun Liu,

    1. Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia
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  • Dan Wang,

    1. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, PR China
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  • Ying Li,

    1. Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia
    2. School of Materials Science and Engineering, Shanghai University, Shanghai, 200072, PR China
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  • Huijun Zhao

    Corresponding author
    1. Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia
    • Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland 4222, Australia.
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Abstract

Cross-linked rather than non-covalently bonded graphitic carbon nitride (g-C3N4)/reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g-C3N4, the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C−O−C covalent bonding between the rGO and g-C3N4 layers, which is experimentally confirmed by Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4-nitrophenol under visible light irradiation (λ > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO-2.5% nanocomposite exhibits the highest photocatalytic efficiency, which is almost 3.0 and 2.7 times that of pure g-C3N4 toward photocatalytic degradation of RhB and 4-nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the significantly narrowed bandgap, positively shifted valence band-edge potential, and enhanced electronic conductivity.

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