Preferential Vapor Nucleation on Hierarchical Tapered Nanowire Bunches
Preferential Vapor Nucleation on Hierarchical Tapered Nanowire Bunches
复制标题
分层锥形纳米线束上的优先蒸气成核
DOI：
10.1021/acs.langmuir.0c03125
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发表时间：
2021-01-19
期刊：
影响因子：
3.9
通讯作者：
Ma, Xuehu
中科院分区：
文献类型：
--
作者：
Du, Bingang;Cheng, Yaqi;Ma, Xuehu
控制微/纳米结构表面的蒸汽成核是实现激发液滴动力学和强化冷凝的关键。然而，由于其纳米尺度和瞬变的性质，其成核现象的潜在机制仍然不清楚，特别是对于复杂结构的表面。通过合理的微/纳米结构表面设计来操纵蒸汽成核是非常具有挑战性的。在这里，我们制作了由锥形纳米线束和纵横交错的微槽组成的分层表面。纳米台阶围绕纳米线束的顶部形成，周围的纳米线由于表面张力而密集聚集。理论分析和分子动力学模拟表明，与位于纳米线束中心和底部的稀疏排列的纳米线相比，位于纳米线束顶部周围的纳米级形貌可以实现更低的能垒和更高的成核能力。蒸汽冷凝实验表明，成核优先发生在纳米线束的顶部附近。这些结果为设计微/纳米结构以促进冷凝过程中的汽相成核和液滴去除提供了指导。
Controlling vapor nucleation on micro-/nanostructured surfaces is critical to achieving exciting droplet dynamics and condensation enhancement. However, the underlying mechanism of nucleation phenomena remains unclear because of its nature of nanoscale and transience, especially for the complex-structured surfaces. Manipulating vapor nucleation via the rational surface design of micro-/nanostructures is extremely challenging. Here, we fabricate hierarchical surfaces comprising tapered nanowire bunches and crisscross microgrooves. Nanosteps are formed around the top of the nanowire bunches, where the nanowires all around agglomerate densely because of surface tension. The theoretical analysis and molecular dynamics simulation show that nanostep morphologies that are around the top of the nanowire bunches can enable a lower energy barrier and a higher nucleation capability than those of the sparsely packed nanowires at the center and bottom of the nanowire bunches. Vapor condensation experiments demonstrate that the nucleation preferentially occurs around the top of the nanowire bunches. The results provide guidelines to design micro-/nanostructures for promoting vapor nucleation and droplet removal in condensation.