Multistep Regioselectivity and Non-Kirkendall Anion Exchange of Copper Chalcogenide Nanorods
Multistep Regioselectivity and Non-Kirkendall Anion Exchange of Copper Chalcogenide Nanorods
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DOI：
10.1021/acs.chemmater.1c01107
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发表时间：
2021-05-17
影响因子：
8.6
通讯作者：
Plass, Katherine E.
中科院分区：
文献类型：
--
作者：
Garcia-Herrera, Luis F.;McAllister, Haley P.;Plass, Katherine E.
改变纳米颗粒组成的化学反应对于光电和催化应用是重要的。了解它们是如何发生的，以及由此产生的独特特征，是设计具有复杂形态的复杂纳米结构的重要先决条件。在这里，我们报告的α-辉铜矿硫化铜纳米棒转化为weissite碲化铜纳米棒通过阴离子交换。通过检查交换后的元素组成、形态和结晶度，发现碲离子以保持（伪）六方密堆积的亚晶格以及形态和结晶度的方式取代硫离子以生成魏氏体。不寻常的是，阴离子交换进行时不会在产物纳米颗粒中引起空隙。通过柯肯达尔效应产生的这种空隙通常在阴离子交换反应期间观察到，但对于避免最小化缺陷可能是重要的。空隙形成的缺乏被解释为由在阴离子交换反应的早期阶段在纳米棒内形成的纳米级路径提供的向内和向外阴离子扩散的平衡。这些交换促进故障的存在下，在一个不寻常的多步骤的过程中改变的碲化铜区域出现在部分交换的位置。三种不同的阴离子运动方式导致三种不同的几何形状。最初，近各向同性交换产生硫化铜/碲化铜核壳结构。随着交换的进行，缺陷介导的运动导致碲化铜内出现形状不规则的硫化铜域。相分离，然后导致一个独特的双核硫化铜/碲化铜异质结构。这项工作提供了深入了解阴离子交换背后的机制，突出了从有缺陷的材料出现的设计能力，并为复杂的纳米异质结构的合理合成创造了新的机会。
Chemical reactions that modify the compositions of nanoparticles are important for optoelectronic and catalytic applications. Understanding how they occur, and the unique features that can be produced as a result, is an important prerequisite to designing intricate nanostructures with complex morphologies. Here, we report the conversion of alpha-chalcocite copper sulfide nanorods into weissite copper telluride nanorods through anion exchange. By examining the elemental composition, morphology, and crystallinity post exchange, it was found that the tellurium ions replaced sulfur ions to generate weissite in a way that maintained the (pseudo-)hexagonally close-packed sublattice as well as the morphology and crystallinity. Unusually, the anion exchange proceeded without inducing voids in the product nanoparticles. Such voids, produced through the Kirkendall effect, are commonly observed during nanocrystal anion exchange reactions, yet can be important to avoid minimizing defects. The lack of void formation was explained by the balancing of inward and outward anion diffusion offered by nanoscopic pathways that formed within the nanorods at the early stages of the anion exchange reaction. The presence of these exchange-facilitating faults results in an unusual multistep process altering the locations at which copper telluride regions emerged during partial exchange. Three different anion movement regimes resulted in three distinct geometries. Initially, a near-isotropic exchange produced a copper sulfide/copper telluride core-shell structure. As the exchange progressed, the defect-mediated movement resulted in irregularly shaped copper sulfide domains within copper telluride. Phase segregation then led to a unique double-core copper sulfide/copper telluride heterostructure. This work offers insights into the mechanism behind anion exchange, highlights the design capabilities emergent from defective materials, and creates new opportunities for rational synthesis of complex nanoheterostructures.