Crystalline heptazine carbon nitride (HCN) is an ideal photocatalyst for photocatalytic ammonia synthesis. However, the limited response to visible light has hindered its further development. As a noble metal, Au nanoparticles (NPs) can enhance the light absorption capability of photocatalysts by the surface plasmon resonance (SPR) effect. Therefore, a series of Au NPs-loaded crystalline carbon nitride materials (AH) were prepared for photocatalytic nitrogen fixation. The results showed that the AH displayed significantly improved light absorption and decreased recombination rate of photo-generated carriers owing to the introduction of Au NPs. The optimal 2AH (loaded with 2 wt% Au) sample demonstrated the best photocatalytic performance for ammonia production with a yield of 70.3 μmol g− 1 h− 1, which outperformed that of HCN. This can be attributed to the SPR effect of Au NPs and alkali metal of HCN structure. These findings provide a theoretical basis for studying noble metal-enhanced photocatalytic activity for nitrogen fixation and offer new insights into advances in efficient photocatalysts.

Au-loaded alkali metal-modified crystalline carbon nitride for photocatalytic nitrogen fixation
    Abstract
    1 Introduction
    2 Experimental sections
        2.1 Materials
        2.2 Preparation
            2.2.1 The synthesis of alkali metal-modified crystalline g-C3N4 (HCN):
            2.2.2 The synthesis of Au NPs-supported alkaline modified crystalline g-C3N4 (AuHCN)
        2.3 Material characterization
        2.4 Photoelectronic measurement
        2.5 Photocatalytic reactions
    3 Results and discussion
        3.1 Synthetic strategy and structure of the samples
        3.2 Microstructure characterization
        3.3 Element composition and chemical state
        3.4 Optical and photochemical properties
        3.5 Photocatalytic ammonia performance and mechanism
    4 Conclusions
    Acknowledgements 
    References

• Mimi Luo(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China)
• Baibing Wang(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China)
• Jiahui Shao(College of Marine Science and Technology, Dalian University of Technology, Liaoning 116024, China)
• Yupeng Yan(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China)
• Guanjie Jiang(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China)
• Qin Zhang(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China)
• Yang Li(Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China) Corresponding author