Ultrafast Reaction Mechanisms in Perovskite Based Photocatalytic C–C Coupling
Ultrafast Reaction Mechanisms in Perovskite Based Photocatalytic C–C Coupling
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DOI：
10.1021/acsenergylett.9b02714
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发表时间：
2020-01
影响因子：
22
通讯作者：
Kang Wang;Haipeng Lu;Xiaolin Zhu;Yixiong Lin;M. Beard;Yong Yan;Xihan Chen
中科院分区：
文献类型：
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作者：
Kang Wang;Haipeng Lu;Xiaolin Zhu;Yixiong Lin;M. Beard;Yong Yan;Xihan Chen
太阳能驱动的碳-碳（C-C）键形成是太阳能利用的一个新方向。地球上丰富的稀土基光催化剂受到高度追捧，因为它们可以潜在地消除昂贵的贵金属催化剂。对潜在反应机制的详细了解可以为设计可以激活更大类小分子的新系统提供指导。在这里，我们采用瞬态吸收光谱来研究模型C-C键形成反应，即，胶体CsPbBr 3纳米晶催化醛的α-烷基化反应。我们发现，电子和空穴进行超快的电荷转移（1050 ps）从光激发的钙钛矿NC反应物分子。电荷分离态的寿命超过0.8 μs，使自由基机制能够形成C-C键。讨论了纳米碳光氧化还原催化剂与分子催化剂的区别。
Solar driven carbon–carbon (C–C) bond formation is a new direction in solar energy utilization. Earth abundant nanocrystal based photocatalysts are highly sought after as they can potentially eliminate expensive noble metal catalysts. A detailed understanding of the underlying reaction mechanisms could provide guidance in designing new systems that can activate a larger class of small molecules. Here, we employ transient absorption spectroscopy to study a model C–C bond formation reaction, i.e., α-alkylation of aldehydes catalyzed by colloidal CsPbBr3 nanocrystals (NCs). We find that both electrons and holes undergo ultrafast charge transfer (∼50 ps) from photoexcited perovskite NCs to reactant molecules. A charge separated state lives for more than 0.8 μs, enabling a radical mechanism to form the C–C bonds. We discuss the differences between the NCs photoredox catalysts and the molecular catalyst.