Tunable Layer Orientation and Morphology in Vapor–Liquid–Solid Growth of One-Dimensional GeS van der Waals Nanostructures
Tunable Layer Orientation and Morphology in Vapor–Liquid–Solid Growth of One-Dimensional GeS van der Waals Nanostructures
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DOI：
10.1021/acs.chemmater.1c00289
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发表时间：
2021-06
影响因子：
8.6
通讯作者：
E. Sutter;Jacob S. French;P. Sutter
中科院分区：
文献类型：
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作者：
E. Sutter;Jacob S. French;P. Sutter
蒸汽-液-固（VLS）层状晶体的生长产生了范德华纳米线，这是一种新兴的一维（1D）纳米结构。范德华材料的晶体结构，层内共价键和层间弱相互作用，不仅产生了高度的各向异性，而且为在VLS生长过程中控制层的取向提供了机会。本文以一维锗范德华纳米结构为模型体系，通过在VLS催化剂中添加添加剂，可以实现这种控制。在纯锗酸盐前驱体中，金催化的VLS生长总是会产生沿纳米线轴线分层的锗酸盐纳米线。在GeS蒸气中添加少量的SnS，可重复地将形貌切换为具有两种不同层堆叠几何形状的高质量带状GeS纳米结构，“倾斜带”由两个不对齐的半部分组成，层堆叠平行于带轴，以及“倾斜带”，其中一组GeS片倾斜远离纳米线轴。TEM成像和化学分析表明，SnS并没有加入到生长的条带中，而是被限制在VLS滴中，其作用可能是改变催化剂滴对GeS片的润湿，从而改变形貌和层向。对单个GeS纳米带的阴极发光测量表明，两种类型的条带之间的发射变化很小，而整体光电性能保持GeS的特性。我们的研究结果表明，通过对气-液-固生长过程中使用的催化剂进行修饰，可以定制一维范德华纳米结构的形态。
Vapor–liquid–solid (VLS) growth of layered crystals produces van der Waals nanowires, an emerging class of one-dimensional (1D) nanostructures. The crystal structure of van der Waals materials, covalently bonded within and weakly interacting between the layers, not only gives rise to highly anisotropic properties but also provides opportunities for controlling the layer orientation in VLS growth processes. Here, we show that such control can be realized via additives to the VLS catalyst, using 1D GeS van der Waals nanostructures as a model system. Au-catalyzed VLS growth from a pure GeS precursor invariably yields GeS nanowires with layering along the nanowire axis. Adding a small amount of SnS to the GeS vapor reproducibly switches the morphology to high-quality ribbonlike GeS nanostructures with two different layer stacking geometries, “angled ribbons” consisting of two misaligned halves with layer stacking parallel to the ribbon axis, and “tilted-layer ribbons” in which a single set of GeS sheets is tilted away from the nanowire axis. TEM imaging and chemical analysis show that SnS is not incorporated in the growing ribbons but remains confined to the VLS drop where its likely role is to change the wetting of GeS sheets by the catalyst drop, thus modifying the morphology and layer orientation. Cathodoluminescence measurements on individual GeS nanoribbons demonstrate small modifications of the emission between the two types of ribbons, while the overall optoelectronic properties remain those of GeS. Our results demonstrate opportunities for tailoring the morphology of 1D van der Waals nanostructures by modifications to the catalyst used in vapor–liquid–solid growth processes.