Filming evolution dynamics of Hg nanodroplets mediated at solid-gas and solid-liquid interfaces by in-situ TEM.

Nanodroplets at multiphase interfaces are ubiquitous in nature with implications ranging from fundamental interfacial science to industrial applications including catalytic, environmental, biological and medical processes. Direct observation of full dynamic evolutions of liquid metal nanodroplets at nanoscale multiphase interfaces offers indispensable insights, however, remains challenging and unclear. Here, we fabricate gas and liquid cells containing HgS nanocrystals through electrospinning and achieve the statistical investigations of full picture of Hg nanodroplets evolving at solid-gas and solid-liquid interfaces by in-situ transmission electron microscopy. In the gas cells, the voids nucleate, grow and coalesce into the crack-like feature along the <001> direction, while Hg nanodroplets form, move rapidly on the ratchet surface and are evolved into bigger ones through the nanobridges. Distinctly, mediated by the solid-liquid interface, the liquid Hg with the ink-like feature jets in the liquid cells. Such ink-jetting behavior occurs multiple times with the intervals from several to several tens of seconds, which is modulated through the competition between reductive electrons and oxidative species derived from the radiolysis of liquids. In-depth understanding of distinct nanodroplets dynamics at nanoscale solid-gas and solid-liquid interfaces offers a feasible approach for designing liquid metal-based nanocomplexes with regulatory interfacial, morphological and rheological functionalities.