Acta Chimica Sinica ›› 2021, Vol. 79 ›› Issue (7): 914-919.DOI: 10.6023/A21030121 Previous Articles     Next Articles



麻旺坪, 贺彦彦, 刘洪来*()   

  1. 华东理工大学 化学工程联合国家重点实验室 化学与分子工程学院 上海 200237
  • 投稿日期:2021-03-30 发布日期:2021-06-16
  • 通讯作者: 刘洪来
  • 基金资助:

Olefin-linked Conjugated Porous Networks and Their Visible-Light-Driven Hydrogen Evolution Performance

Wangping Ma, Yanyan He, Honglai Liu()   

  1. School of Chemistry and Molecular Engineering, State Key Laboratory of Chinese Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2021-03-30 Published:2021-06-16
  • Contact: Honglai Liu
  • Supported by:
    National Natural Science Foundation of China(91834301)

Global energy storage and environmental pollution have received increasing attention, and finding sustainable clean energy to replace fossil fuels has become an urgent issue. Visible-light-driven photocatalytic water splitting can not only obtain clean hydrogen energy, but also can store solar energy. Therefore, great efforts have been put into research and it has consequently developed rapidly. In recent years, different types of photocatalysts, such as inorganic materials, metal complexes, organic dyes and porous organic networks, have been extensively explored. Among these photocatalysts, conjugated porous networks (CPNs) have attracted much attention due to their adjustable structures, high specific surface area and high structural stability. The band gap and the specific surface area of materials is significant to photocatalytic performance. Hence, exploring appropriate band gap and porosity of materials is the main challenge, which can be achieved by changing the reaction methods and reactants to adjust the materials structure. In this article, unsubstituted olefin-linked (C=C) CPNs through Horner-Wadsworth-Emmons (HWE) reaction have been designed, which are the structure of disubstituted benzene and trimethyltriazine connected by C=C bond (TB-CPN) and the structure of triphenylamine and trimethyltriazine connected by C=C bond (TT-CPN) respectively. In this method, organic base (t-BuOK) was used as a catalyst, and finished the reaction at room temperature, which cost less energy. The entire synthesis procedure takes relatively short time, compared with other polymeric means costing 72 h or 48 h. Firstly, the formation of olefin (C=C) bonds was characterized by Fourier transform infrared (FT-IR) spectroscopy. Next, the structure of the polymers was further confirmed by solid-state nuclear magnetic resonance. Nitrogen adsorption-desorption measurement was applied to examine the porosity of the polymers, it showed that TT-CPN has a larger specific surface area than TB-CPN. The band gap of TT-CPN and TB-CPN obtained by UV-Vis diffuse reflection spectra is 2.22 and 2.30 eV, respectively. After that, the two polymers were used as photocatalysts to investigate the visible-light-driven hydrogen evolution by water splitting. Of these, the porous polymer TT-CPN reveals a better photocatalytic behavior with a hydrogen evolution rate of 913.3 μmol•h -1•g-1. Under the same testing condition, the hydrogen evolution rate of TB-CPN was only 86% of TT-CPN. Besides, after TT-CPN was continuously irradiated under visible light for 25 h, its photocatalytic activity barely decreased, showing good photochemical stability and repeatability. In a word, in this article, a method with low-temperature and short reaction time was developed to synthesize C=C bond connected conjugated porous networks, and the polymers were used for efficient photocatalytic water splitting to produce hydrogen under visible light irradiation. This method may provide a new choice for the design and synthesis of porous polymers as photocatalysts.

Key words: low-temperature synthesis, olefin-linkage, conjugated porous networks, photocatalysis, hydrogen evolution