Efficient and Selective Photogeneration of Stable N-Centered Radicals via Controllable Charge Carrier Imbalance in Cesium Lead Halide Nanocrystals
Efficient and Selective Photogeneration of Stable N-Centered Radicals via Controllable Charge Carrier Imbalance in Cesium Lead Halide Nanocrystals
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DOI：
10.1021/jacs.3c05323
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发表时间：
2023-07
影响因子：
15
通讯作者：
Tian Qiao;Madison E. Edwards;Xueting Tang;Xin Yan;D. Son
中科院分区：
文献类型：
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作者：
Tian Qiao;Madison E. Edwards;Xueting Tang;Xin Yan;D. Son
尽管半导体纳米晶体（NC）在光诱导化学过程中的多功能性，但由于即使在牺牲电荷受体存在下的反向电荷转移或电荷重组，稳定自由基的产生也更具挑战性。在这里，我们表明，铯铅卤化物（CsPbX 3）NC可以选择性地从胺光生铵或胺基自由基，利用可控的不平衡的电子和空穴群体实现通过改变溶剂组合物。使用二卤代甲烷作为溶剂，通过NC和二卤代甲烷之间的光诱导卤化物交换实现的电子从CsPbX 3 NC的不可逆去除导致铵自由基的有效氧化生成。在溶剂中的二卤甲烷的情况下，电子和空穴的可用性导致在生产的氨基自由基通过顺序的空穴转移和还原性N-H键解离。在NC的晶格表面上的卤素离子的负电荷似乎促进氨基自由基的产生，有利地与可逆的电荷转移恢复到反应物竞争。
Despite the versatility of semiconductor nanocrystals (NCs) in photoinduced chemical processes, the generation of stable radicals has been more challenging due to reverse charge transfer or charge recombination even in the presence of sacrificial charge acceptors. Here, we show that cesium lead halide (CsPbX3) NCs can selectively photogenerate either aminium or aminyl radicals from amines, taking advantage of the controllable imbalance of the electron and hole populations achieved by varying the solvent composition. Using dihalomethane as the solvent, irreversible removal of the electrons from CsPbX3 NCs enabled by the photoinduced halide exchange between the NCs and the dihalomethane resulted in efficient oxidative generation of the aminium radical. In the absence of dihalomethane in solvent, the availability of both electrons and holes resulted in the production of an aminyl radical via sequential hole transfer and reductive N–H bond dissociation. The negative charge of the halide ions on the NC’s lattice surface appears to facilitate the aminyl radical production, competing favorably with the reversible charge transfer reverting to the reactant.