Regioselective Growth Mechanism of Single Semiconductor Tips on CdS Nanorods
Regioselective Growth Mechanism of Single Semiconductor Tips on CdS Nanorods
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DOI：
10.1021/acs.chemmater.0c03636
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发表时间：
2020-12
影响因子：
8.6
通讯作者：
Florian Enders;Sebastian Sutter;Danja Fischli;Rebecca Köser;Samuel Monter;Simon Cardinal;K. Boldt
中科院分区：
文献类型：
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作者：
Florian Enders;Sebastian Sutter;Danja Fischli;Rebecca Köser;Samuel Monter;Simon Cardinal;K. Boldt
由两个或两个以上组分组成的复杂的各向异性纳米晶体是非常有趣的功能材料，可以驱动电荷分离和光催化等定向的光激活过程。然而，尽管存在一些合成方案，但对于第二种半导体材料在纳米晶体种子上区域选择性、非均相成核的反应机理知之甚少。本文介绍了导致单端单尖生长的机制，其产率在50%-80%之间。结果表明，只有一个尖端的生长是由于反应溶液中的可用成核单体在较大的硫化物过量下工作而严格控制的结果。促进这一反应途径的条件的特征是均匀生长的动力学障碍。这与形成亚稳态魔术大小星团的条件相匹配。通过这一边界条件，可以理解为什么与硒和硫化物相比，碲化物尖端的形成更有利，因为对于硒和硫化物来说，团簇形成和表面成核的区域不重叠。
Complex, anisotropic nanocrystals made from two or more components are extremely interesting functional materials that can drive directional, light-activated processes like charge separation and photocatalysis. However, while some synthetic protocols exist, little is known about the reaction mechanism for regioselective, heterogeneous nucleation of a second semiconductor material onto nanocrystal seeds. This paper presents the mechanism that leads to growth of a single tip at one end of CdS nanorods with yields between 50 and 80%. It is shown that the growth of only one tip is a result of tight control of the available, nucleating monomer in the reaction solution by working at a large chalcogenide excess. Conditions that facilitate this reaction pathway are characterized by a kinetic barrier to homogeneous growth. These match those for the formation of metastable magic-size clusters. Through this boundary condition, it can be understood why the formation of telluride tips is favored in comparison to selenides and sulfides, for which the regimes for cluster formation and nucleation on surfaces do not overlap.