物理化学学报 >> 2025, Vol. 41 >> Issue (12): 100160.doi: 10.1016/j.actphy.2025.100160

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利用飞秒瞬态吸收光谱研究pH值对质子化COF光催化H2O2生成的影响

周欣1,2,3, 霍怡廷2, 杨松瑀3, 何博文3, 王晓晶1,*(), 吴珍2,*(), 张建军3,*()   

  1. 1 内蒙古大学化学化工学院, 内蒙古 呼和浩特 010021
    2 鄂尔多斯应用技术学院化学工程学院, 内蒙古 鄂尔多斯 017000
    3 中国地质大学(武汉)材料与化学学院太阳能燃料实验室, 湖北 武汉 430078
  • 收稿日期:2025-07-25 修回日期:2025-08-12 录用日期:2025-08-14 发布日期:2025-10-23
  • 通讯作者: Email: wang_xiao_jing@hotmail.com (王晓晶)wuzhen@oit.edu.cn (吴珍)zhangjianjun@cug.edu.cn (张建军)
  • 基金资助:
    国家自然科学基金(52202375); 国家自然科学基金(22469001); 国家自然科学基金(22409181); 湖北省自然科学基金(2022CFA001); 湖北省自然科学基金(2025AFB631); 鄂尔多斯应用技术学院科研项目(KYQN25Z012); 鄂尔多斯应用技术学院科研项目(KYYB2023014); 中国地质大学(武汉)中央高校基本科研业务费专项资金(2025034); 内蒙古自治区自然科学基金(2025QN05107); 内蒙古自治区自然科学基金(2025ZDLH002)

Understanding the effect of pH on protonated COF during photocatalytic H2O2 production by femtosecond transient absorption spectroscopy

Xin Zhou1,2,3, Yiting Huo2, Songyu Yang3, Bowen He3, Xiaojing Wang1,*(), Zhen Wu2,*(), Jianjun Zhang3,*()   

  1. 1 College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, Inner Mongolia Autonomous Region, China
    2 Department of Chemical Engineering, Ordos Institute of Technology, Ordos, 017000, Inner Mongolia Autonomous Region, China
    3 Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, Hubei Provicne, China
  • Received:2025-07-25 Revised:2025-08-12 Accepted:2025-08-14 Published:2025-10-23
  • Contact: Email: wang_xiao_jing@hotmail.com (Xiaojing Wang)wuzhen@oit.edu.cn (Zhen Wu)zhangjianjun@cug.edu.cn (Jianjun Zhang)
  • Supported by:
    National Natural Science Foundation of China(52202375); National Natural Science Foundation of China(22469001); National Natural Science Foundation of China(22409181); the Natural Science Foundation of Hubei Province of China(2022CFA001); the Natural Science Foundation of Hubei Province of China(2025AFB631); Ordos Institute of Technology Research Programs(KYQN25Z012); Ordos Institute of Technology Research Programs(KYYB2023014); the Scientific Research Funds at China University of Geosciences (Wuhan)(2025034); Natural Science Foundation of Inner Mongolia Autonomous Region of China(2025QN05107); Natural Science Foundation of Inner Mongolia Autonomous Region of China(2025ZDLH002)

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摘要：

共价有机框架材料(COFs)因其结构可精确调控且具有高比表面积，被认为是极具前景的过氧化氢(H2O2)光催化合成材料。然而，pH值对COFs在光催化合成H2O2过程中稳定性的关键影响尚不明确。本研究通过简单质子化策略显著提升了亚胺连接型COF的光催化H2O2合成性能。值得注意的是，质子化COF在弱酸性条件(pH ≥ 3)下表现出优异的稳定性，但在强酸性条件(pH < 3)下会发生不可逆水解。质子化过程发生在亚胺单元的氮原子上，具有双重功能：抑制超快电荷复合(由飞秒瞬态吸收光谱证实)以及直接为H2O2生成提供质子源。此外，在光催化体系中引入氟离子(F−)可进一步提高H2O2产率，F−的强电负性促进了电子从COF向F−转移，从而实现光生载流子的空间分离。机理研究证实H2O2通过双电子氧还原反应路径生成。这些发现阐明了质子化COFs的pH依赖性稳定性与活性，为载流子转移动力学提供了思路，并为开发高效稳定的COF基光催化剂用于太阳能驱动H2O2合成确立了设计原则。

关键词: 共价有机框架, 结构稳定性, 质子化, 氟离子表面修饰, 飞秒瞬态吸收光谱

Abstract:

Covalent organic frameworks (COFs), recognized for their precisely tunable microstructures and high surface area, are promising photocatalysts for H2O2 production. However, the critical influence of pH on the stability of COF during the photocatalytic H2O2 production remains poorly understood. In this work, the photocatalytic H2O2 production performance of an imine-linked COF is significantly enhanced through a simple protonation strategy. Crucially, the protonated COF exhibits excellent stability under weakly acidic conditions (pH ≥ 3), but undergoes irreversible hydrolyzed under strongly acidic conditions (pH < 3). The protonation occurs specifically at the nitrogen atoms of imine units and serves a dual function: it suppresses ultrafast charge recombination (as revealed by femtosecond transient absorption spectroscopy) and directly provides a proton source for H2O2 generation. Moreover, fluoride ions (F−) are introduced into the photocatalytic system to further improve the photocatalytic H2O2 production rate. The strong electronegativity of F− facilitates electron transfer from COF to F−, thus realizing the spatial separation of photogenerated carriers. Mechanistic studies confirm that H2O2 production follows a two-electron oxygen reduction reaction pathway. These findings elucidate the pH-dependent stability and activity of protonated COFs, provide fundamental insights into charge carrier dynamics, and establishe design principles to develop highly efficient and stable COF-based photocatalysts for solar-driven H2O2 generation.

Key words: Covalent organic frameworks, Structural stability, Protonation, Fluoride ion surface modification, Femtosecond transient absorption spectroscopy