催化学报 ›› 2023, Vol. 46: 91-102.DOI: 10.1016/S1872-2067(22)64159-7

• 论文 • 上一篇    下一篇

理论设计和实验研究吡啶掺杂聚合氮化碳提升光催化CO2还原性能

陈成成a, 刘芳庭a, 张巧钰a, 张正国a,c, 刘琼b,*(), 方晓明a,c,*()   

  1. a华南理工大学化学与化工学院, 传热强化与过程节能教育部重点实验室, 广东广州 510640
    b广东省科学院测试分析研究所(中国广州分析测试中心), 广东广州 510070
    c华南理工大学广东省热能高效储存与利用工程技术研究中心, 广东广州 510640
  • 收稿日期:2022-09-29 接受日期:2022-11-02 出版日期:2023-03-18 发布日期:2023-02-21
  • 通讯作者: *电子信箱: cexmfang@scut.edu.cn (方晓明),liuqiong@fenxi.com.cn (刘琼)
  • 基金资助:
    广东省自然科学基金(2022A1515011737);广东省科学院科技发展项目(2021GDASYL-20210102010)

Theoretical design and experimental study of pyridine-incorporated polymeric carbon nitride with an optimal structure for boosting photocatalytic CO2 reduction

Chengcheng Chena, Fangting Liua, Qiaoyu Zhanga, Zhengguo Zhanga,c, Qiong Liub,*(), Xiaoming Fanga,c,*()   

  1. aKey Laboratory of Heat Transfer Enhancement and Energy Conservation of Education Ministry, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, Guangdong, China
    bInstitute of Analysis, Guangdong Academy of Sciences (China National Analytical Center, Guangzhou), Guangzhou 510070, Guangdong, China
    cGuangdong Engineering Technology Research Center of Efficient Heat Storage and Application, South China University of Technology, Guangzhou 510640, Guangdong, China
  • Received:2022-09-29 Accepted:2022-11-02 Online:2023-03-18 Published:2023-02-21
  • Contact: *E-mail: cexmfang@scut.edu.cn (X. Fang), liuqiong@fenxi.com.cn (Q. Liu)
  • Supported by:
    Natural Science Foundation of Guangdong Province(2022A1515011737);The Guangdong Academy of Sciences Project of Science and Technology Development(2021GDASYL-20210102010)

摘要:

光催化CO2还原是利用太阳光和水将CO2转化为高价值化学品或燃料(如CO、甲醇、甲烷等), 被认为是解决CO2问题的理想途径之一.  CO2分子中C=O离解能高而活化困难, 且光催化CO2还原涉及多质子耦合多电子转移过程且产物多样, 因而研制效率高且选择性好的光催化剂是该技术的关键.  聚合物氮化碳(PCN)作为一种结构可调的有机光催化剂, 具有化学稳定性好且能带位置适宜于还原CO2的优势, 是一种具有发展潜力的CO2还原光催化剂;  但是PCN也存在因其禁带宽度较大而对可见光响应范围有限以及因其结构由三均三嗪单元构成而缺乏足够活性位点来吸附和活化CO2等不足.  目前在提升PCN的光催化CO2还原性能方面已有不少研究, 但所得的PCN基光催化剂在效率和选择性上仍处于较低水平.  考虑到光催化CO2还原涉及复杂的热力学和动力学要求, 对基于PCN的光催化剂进行精准设计和研究是非常必要的, 这有望获得同时具有可见光吸收增强、光生载流子复合减少、吸附和活化CO2的位点增加以及能带位置适宜等特性的高性能光催化剂.  为此, 本论文采用理论设计与实验研究相结合的方法, 以吡啶掺杂PCN为模型, 研制了一种用于CO2还原的高性能PCN基光催化剂.  

本文设计了将吡啶掺杂到PCN结构单元中不同位置的两种结构, 并运用理论计算确定其中禁带宽度较窄、更利于光生载流子分离、更有助于CO2吸附和活化以及总能量较低的结构作为最优结构.  然后, 采用尿素与适量的2-氨基吡啶共聚的方法, 制备了吡啶掺杂的PCN样品, 并通过一系列表征确定结构设计成功.  还测定了所得吡啶掺杂PCN样品的光学和光电化学特性, 评价了它们光催化CO2还原的活性和选择性.  最后, 通过理论计算和实验研究, 阐明了该吡啶掺杂PCN光催化剂的性能增强机制及其光催化还原CO2的反应路径.  结果表明, 以CO(bpy)2为助催化剂, 本文制备的吡啶掺杂PCN(CN-5%AP)光催化剂不仅取得了较高的CO产量, 而且还获得99.6%的CO选择性, 在λ = 420 nm处的表观量子效率可达2.86%.  研究表明, 该吡啶掺杂的PCN光催化性能增强主要源于其提升的CO2吸附容量以及对CO2还原为CO反应的促进.  综上, 本工作为设计和制备实现高效CO2还原的光催化剂提供了参考.

关键词: 光催化CO2还原, 先理论后实验, 聚合氮化碳, 密度泛函理论, 吡啶

Abstract:

Herein, pyridine-incorporated polymeric carbon nitride (PCN) was explored for boosting photocatalytic CO2 reduction. First, theoretical calculations were performed on PCN models with pyridine molecules located at different positions to determine the optimal structure of pyridine-incorporated PCN with the lowest total energy, smallest bandgap, and most efficient CO2 adsorption and activation processes. Subsequently, pyridine-incorporated PCN with the optimal structure was prepared experimentally by copolymerizing urea and 2-aminopyridine (AP). A high CO evolution rate with a selectivity of 99.6% was achieved by combining CN-5%AP with a Co(bpy)2 co-catalyst, which resulted an apparent quantum efficiency of 2.86% at λ = 420 nm. The high performance of pyridine-incorporated PCN mainly originated from its strong CO2 adsorption ability and facilitation of the CO2-to-CO reduction reaction. This work paves the way for the precise design and preparation of photocatalysts with high CO2 reduction efficiency.

Key words: Photocatalytic CO2 reduction, Theoretical first and then experiment, Polymeric carbon nitride, Density functional theory, Pyridine