Chinese Journal of Catalysis ›› 2021, Vol. 42 ›› Issue (9): 1608-1616.DOI: 10.1016/S1872-2067(20)63776-7

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Construction of efficient active sites through cyano-modified graphitic carbon nitride for photocatalytic CO2 reduction

Fang Lia,b, Xiaoyang Yuea, Haiping Zhouc, Jiajie Fand, Quanjun Xianga,b,*()   

  1. aState Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, Sichuang, China
    bYangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, Zhejiang, China
    cSchool of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 610054, Sichuang, China
    dSchool of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450002, Henan, China
  • Received:2021-01-12 Accepted:2021-02-01 Online:2021-09-18 Published:2021-05-16
  • Contact: Quanjun Xiang
  • About author:* Tel/Fax: +86-28-83207063; E-mail: xiangqj@uestc.edu.cn
    Quanjun Xiang received his Ph.D. degree in materials chemistry and physics in 2012 from Wuhan University of Technology. He was a postdoctoral fellow at the City University of Hong Kong from 2013 to 2015, and an associate professor from 2012 to 2017 at Huazhong Agricultural University. He is now a professor at the School of Electronic Science and Engineering, University of Electronic Science and Technology of China. His research interests include semiconductor photocatalysis, photocatalytic hydrogen production, CO2 reduction to hydrocarbon fuels. He has coauthored about 80 peer-reviewed papers, and these articles have been cited more than 12320 times by SCI. He has won the award of “Highly Cited Researchers” by Thomson Reuters and/or Clarivate Analytics for the third consecutive year in 2016-2020. In addition, he obtains 2 first prize in natural science of Hubei Province in 2016 and 2018, and the 17th young teacher award by Fok Ying Tong education foundation. He joined the editorial board of Chinese Journal of Catalysis in 2020.
  • Supported by:
    National Natural Science Foundation of China(51672099);National Natural Science Foundation of China(52073263);Sichuan Science and Technology Program(2019JDRC0027);Sichuan Science and Technology Program(2019YFG0222);Fundamental Research Funds for the Central Universities(2017-QR-25)

Abstract:

The active site amount of photocatalysts, being the key factors in photocatalytic reactions, directly affects the photocatalytic performance of the photocatalyst. Pristine graphitic carbon nitride (g-C3N4) exhibits moderate photocatalytic activity due to insufficient active sites. In this study, cyano-modified porous g-C3N4 nanosheets (MCN-0.5) were synthesized through molecular self-assembly and alkali-assisted strategies. The cyano group acted as the active site of the photocatalytic reaction, because the good electron-withdrawing property of the cyano group promoted carrier separation. Benefiting from the effect of the active sites, MCN-0.5 exhibited significantly enhanced photocatalytic activity for CO2 reduction under visible light irradiation. Notably, the photocatalytic activity of MCN-0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid (HCl) treatment, further verifying the role of cyano groups as active sites. The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction. Furthermore, the controlled experiments showed that g-C3N4 grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity, which proved the versatility of the strategy for enhancing the activity of g-C3N4 via cyano group modification. In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO2 reduction by cyano-modified g-C3N4. This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.

Key words: Graphitic carbon nitride, Cyano group modification, Active sites, Electron acceptor, Porous structure, Photocatalytic CO2 reduction