Long-lived photoinduced charge separation in a redox system trapped in a sol–gel glass
Long-lived photoinduced charge separation in a redox system trapped in a sol–gel glass
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DOI：
10.1038/355240a0
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发表时间：
1992
期刊：
影响因子：
64.8
通讯作者：
A. Slama-Schwok;M. Ottolenghi;D. Avnir
中科院分区：
文献类型：
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作者：
A. Slama-Schwok;M. Ottolenghi;D. Avnir
光合作用机制的一个关键特征是以长寿命自由基对的形式初始存储大部分光能。在人工系统2-4中模拟这一过程的尝试中，在提高激发的光敏剂和适当的电子受体之间的电荷分离反应的效率方面取得了令人印象深刻的进展，但防止对中性物质的浪费能量的逆反应仍然构成主要挑战。逆反应限制了电荷分离（以及能量存储）可以维持的时间长度。在这里，我们报告了人工光合作用系统中寿命极长（长达几个小时）的光致电荷分离，该系统不需要辅助底物与带电物质反应。我们的系统使用芘 (Py*) 作为光敏电子供体，N,N'-二甲基 1-4,4'-联吡啶鎓（甲基紫精，MV2+）作为电子受体，两者均固定在多孔溶胶-凝胶二氧化硅玻璃中。氧化还原反应是通过孔内空间中第三个移动电荷载体的介导进行的。供体和受体之间的空间分离抑制了逆反应，从而产生电荷分离对的长寿命。
A KEY feature in the mechanism of photosynthesis is the initial storage of a substantial fraction of the light energy in the form of a long-lived radical pair1. In attempts to mimic this process in artificial systems2–4, impressive progress has been made in increasing the efficiency of the charge-separation reaction between an excited photosensitizer and an appropriate electron acceptor, but prevention of the energy-wasting back-reaction to neutral species still constitutes a major challenge. The back-reaction limits the length of time during which charge separation (and thus energy storage) can be maintained. Here we report exceedingly long-lived (up to a few hours) photoinduced charge separation in an artificial photosynthetic system that does not require a secondary substrate to react with the charged species. Our system uses pyrene (Py*) as the photosensitized electron donor andN,N'-dimethy 1-4,4'-bipyridinium (methyl viologen, MV2+) as the electron acceptor, both immobilized in a porous sol–gel silica glass5. The redox reaction is carried out by the mediation of a third mobile charge carrier in the intrapore space6. The spatial separation between the donor and acceptor inhibits the back-reaction to produce the long lifetimes of the charge-separated pair.