The vapor–liquid–solid (VLS) method is vastly employed to grow hierarchical structures with unique properties. However, key questions remain, such as what controls the branched structures and what the roles of the catalyst droplet size are during the growth. Here, an in-depth understanding of the kinetics of the nucleation, growth, and subsequent coalescence processes of Bi liquid catalyst droplets is provided by direct observation of PbSe branched wire growth in an environmental transmission electron microscope. This brings a kinetic control of the branch density by varying the parameters, such as temperature. In addition, the dependence of the wire growth rate on the catalyst droplet size is revealed, i.e., the smaller the catalyst size the larger the wire growth rate, unlike the wire growth controlled by the Gibbs–Thomson effect, possibly due to different mass transport pathways and atomic surface diffusion. These results extend the fundamental understanding of the VLS growth mechanism of branched structures and benefit the structure design of hierarchical materials with tailored properties.

中文翻译：

---

催化剂液滴对VLS生长过程中金属丝生长及分支结构的影响

气液固（VLS）法被广泛用于生长具有独特性质的分层结构。然而，关键问题仍然存在，例如什么控制分支结构以及催化剂液滴尺寸在生长过程中起什么作用。在这里，通过在环境透射电子显微镜中直接观察PbSe分支线的生长，可以深入了解Bi液体催化剂液滴的成核，生长和随后的聚结过程的动力学。通过改变参数（例如温度），可以动态控制分支密度。另外，揭示了焊丝生长速率对催化剂液滴尺寸的依赖性，即，催化剂尺寸越小，金属线的生长速率就越大，这与吉布斯-汤姆森效应控制的金属线生长不同，这可能是由于不同的质量传递途径和原子表面扩散所致。这些结果扩展了对分支结构的VLS生长机理的基本理解，并有益于具有定制属性的分层材料的结构设计。