Ultrafast Reaction Mechanisms in Perovskite Based Photocatalytic C–C Coupling,ACS Energy Letters

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Ultrafast Reaction Mechanisms in Perovskite Based Photocatalytic C–C Coupling
ACS Energy Letters ( IF 19.3 ) Pub Date : 2020-01-27 , DOI: 10.1021/acsenergylett.9b02714
Kang Wang _{1,

2} , Haipeng Lu ₂ , Xiaolin Zhu ₃ , Yixiong Lin ₃ , Matthew C. Beard ₂ , Yong Yan ₃ , Xihan Chen ₂

Affiliation

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.

中文翻译：

钙钛矿基光催化CC偶联中的超快反应机理

太阳能驱动的碳-碳（CC）键的形成是太阳能利用的新方向。富含地球的纳米晶体基光催化剂备受追捧，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新系统提供指导，该系统可以激活更大种类的小分子。在这里，我们使用瞬态吸收光谱研究模型C–C键形成反应，即胶体CsPbBr ₃催化醛的α-烷基化纳米晶体（NCs）。我们发现电子和空穴都经历了从光激发钙钛矿NCs到反应物分子的超快速电荷转移（〜50 ps）。电荷分离态的寿命超过0.8μs，从而使自由基机理形成了C–C键。我们讨论了NCs光氧化还原催化剂和分子催化剂之间的差异。

更新日期：2020-01-27

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