催化学报 ›› 2022, Vol. 43 ›› Issue (7): 1894-1905.DOI: 10.1016/S1872-2067(21)64026-3

• 论文 • 上一篇    下一篇

利用N-羟基邻苯二甲酰亚胺研究可见光照射下Nb2O5中高度扭曲的NbO6单元作为电子转移位点

苏凯艺a,b, 张超锋a,*(), 王业红a, 张健a, 郭强a, 高著衍a,b, 王峰a,#()   

  1. a中国科学院大连化学物理研究所, 催化基础国家重点实验室, 洁净能源国家实验室(筹), 辽宁大连116023
    b中国科学院大学, 北京100049
  • 收稿日期:2021-12-30 接受日期:2022-01-17 出版日期:2022-07-18 发布日期:2022-05-20
  • 通讯作者: 张超锋,王峰
  • 基金资助:
    国家自然科学基金(2025206);国家自然科学基金(21961130378);国家自然科学基金(21802137);大连市科技创新基金(2019J11CY009);辽宁省振兴英才计划(XLYC2002012);大连市高层次人才创新支撑计划(2020RT10);中国科学院青年创新促进会资助项目(2019185);牛顿高级合作伙伴(NAF\R1\191267)

Unveiling the highly disordered NbO6 units as electron-transfer sites in Nb2O5 photocatalysis with N-hydroxyphthalimide under visible light irradiation

Kaiyi Sua,b, Chaofeng Zhanga,*(), Yehong Wanga, Jian Zhanga, Qiang Guoa, Zhuyan Gaoa,b, Feng Wanga,#()   

  1. aState Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    bUniversity of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-12-30 Accepted:2022-01-17 Online:2022-07-18 Published:2022-05-20
  • Contact: Chaofeng Zhang, Feng Wang
  • Supported by:
    National Natural Science Foundation of China(2025206);National Natural Science Foundation of China(21961130378);National Natural Science Foundation of China(21802137);Dalian Science and Technology Innovation Fund(2019J11CY009);Liaoning Revitalization Talents Program(XLYC2002012);Dalian Innovation Support Plan for High Level Talents(2020RT10);Youth Innovation Promotion Association (YIPA) of the Chinese Academy of Sciences(2019185);Newton Advanced Fellowships(NAF\R1\191267)

摘要:

五氧化二铌(Nb2O5)具有独特酸碱性质和氧化能力, 在光催化尤其是光催化芳香化合物转化中引起了广泛的研究兴趣. 受限于自身的带隙宽度, 单纯Nb2O5只能吸收并利用太阳光中的紫外区能量. 近年来, 在Nb2O5上的可见光催化苄胺和苯甲醇选择氧化报道中, 底物活化和产物的高选择性归因于Nb2O5上Nb位点和底物的直接相互作用, 这系列工作为后续Nb2O5可见光催化过程提供研究基础, 被视为Nb2O5光催化作用研究中的里程碑工作. 此外, 研究发现Nb2O5的形貌改变会导致其活性有明显差异. 研究深入发现Nb2O5基催化剂中存在不同的NbOx单元, 虽然在不同形貌的Nb2O5催化剂上也存在这一结构, 但它们与活性之间的相关性尚不清楚. 为了解决这些问题, 亟需开发时空分辨的表征手段或者探针分子辅助的研究手段. 结合以往的研究报道, 含羟基或胺基官能团的有机分子与Nb位点存在相互作用. 由此推测, 可通过监测特定多官能团探针分子化合物与Nb2O5间存在的强相互作用以及电荷传递过程, 研究表面NbOx结构在光催化过程中的作用.

本文利用N-羟基邻苯二甲酰亚胺(NHPI)为探针分子, 区分不同NbOx结构单元在可见光照射下对C-H键的催化活化作用. 利用水热法及焙烧处理, 制备了含不同扭曲程度NbO6结构的Nb2O5催化剂, 结合紫外可见漫反射光谱、光电子能谱和电子顺磁共振波谱, 发现在可见光照下NHPI的电子明显转移到含高度扭曲NbO6结构的Nb2O5催化剂上. 在可见光(455 nm)照射下评价NHPI和不同Nb2O5催化剂在乙苯氧化反应中的性能, 发现含高度扭曲NbO6结构的催化剂上苯乙酮的生成速率明显高于含低度扭曲NbO6结构的催化剂(419‒495 vs. 82 μmol·g-1·h-1). 结合EPR为电子顺磁共振谱和捕获剂对比试验结果, 表明苯乙酮生成速率差异归因于NHPI失去电子后生成氮氧自由基物种有利于乙苯的C-H键活化, 从而提高乙苯的转化率及产物苯乙酮生产速率. 本文关联高度扭曲NbO6结构和光催化中电荷传递过程, 为研究光催化中NbOx的作用提供参考. 为开发其他探针分子, 实现Nb2O5上C-H键的高效活化, 以及用于开发有机物-Nb2O5的光催化体系提供借鉴.

关键词: 光催化作用, Nb2O5, 高度扭曲NbO6结构单元, 电荷传递过程, N-羟基邻苯二甲酰亚胺

Abstract:

Although different NbOx units are present in Nb2O5-based catalysts, the correlations between these structures and activity remain unclear, which considerably hinders the further development of Nb2O5 photocatalysis. Herein, we utilized N-hydroxyphthalimide (NHPI) as the probe molecule to distinguish the role of different NbOx units in the activation of C-H bond under visible light irradiation. With the addition of NHPI, Nb2O5 catalysts with highly disordered NbO6 units exhibited higher activities than that with slightly disordered NbO6 units (419‒495 vs. 82 μmol·g-1·h-1) in photocatalytic selective oxidation of ethylbenzene. Revealed by Raman spectra, electron paramagnetic resonance spectra, and transmission-electron-microscopy images, highly disordered NbO6 units were confirmed to act as the active sites for the transfer of photogenerated electrons from NHPI, promoting the generation of phthalimide-N-oxyl (PINO) radicals for the enhanced conversion of ethylbenzene under visible light irradiation. This study provides guidance on the role of local NbOx units in Nb2O5 photocatalysis.

Key words: Photocatalysis, Nb2O5, Highly disordered NbO6 units, Charge-transfer process, N-hydroxyphthalimide