【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。更多还原

【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 p H 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 H₂O₂generation.更多还原