Operando film-electrochemical EPR spectroscopy tracks radical intermediates in surface-immobilized catalysts
Operando film-electrochemical EPR spectroscopy tracks radical intermediates in surface-immobilized catalysts
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DOI：
10.1038/s41557-024-01450-y
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发表时间：
2024-02-14
期刊：
影响因子：
21.8
通讯作者：
Roessler，Maxie M.
中科院分区：
文献类型：
--
作者：
Seif-Eddine，Maryam;Cobb，Samuel J.;Roessler，Maxie M.
表面固定化分子氧化还原催化剂是一个新兴的研究领域，在可持续化学领域具有广阔的应用前景。在电催化中，顺磁性物质通常是机械循环中的关键中间体，但传统的原位技术本身就难以检测和跟踪。我们报道了一种新的方法，operando膜-电化学电子顺磁共振谱（FE-EPR），使表面固定化电催化剂的机理研究成为可能。该技术可以在流动条件下、室温下和水溶液中实时跟踪氧化还原反应中形成的自由基。对表面固定化催化剂的详细了解，如本文所示，通过表面固定化氮氧化物的醇氧化催化，可以通过灵敏和定量地检测活性位点顺磁性物质，从而实现反应动力学的分辨率。我们发现，表面电子转移速率（与催化速率相同的数量级）限制了催化效率，这对未来设计更好的表面固定化催化剂具有重要意义。
The development of surface-immobilized molecular redox catalysts is an emerging research field with promising applications in sustainable chemistry. In electrocatalysis, paramagnetic species are often key intermediates in the mechanistic cycle but are inherently difficult to detect and follow by conventional in situ techniques. We report a new method, operando film-electrochemical electron paramagnetic resonance spectroscopy (FE-EPR), which enables mechanistic studies of surface-immobilized electrocatalysts. This technique enables radicals formed during redox reactions to be followed in real time under flow conditions, at room temperature and in aqueous solution. Detailed insight into surface-immobilized catalysts, as exemplified here through alcohol oxidation catalysis by a surface-immobilized nitroxide, is possible by detecting active-site paramagnetic species sensitively and quantitatively operando, thereby enabling resolution of the reaction kinetics. Our finding that the surface electron-transfer rate, which is of the same order of magnitude as the rate of catalysis (accessible from operando FE-EPR), limits catalytic efficiency has implications for the future design of better surface-immobilized catalysts.