Filming nanodroplet running and jetting mediated by nanoscale solid-gas and solid-liquid interface

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 the full dynamic evolutions of liquid metal nanodroplets at nanoscale multiphase interfaces offers indispensable insights, however, remains challenging and unclear at the moment. Here, we have fabricated massive ready-to-use gas and liquid cells containing HgS nanocrystals through electrospinning and achieved the statistical investigations of full picture of Hg nanodroplets evolving at solid-gas and solid-liquid interfaces by in-situ transmission electron microscopy. Upon the electron-beam excitation of HgS in the gas cells, the voids nucleated, grew and then coalesced into the crack-like feature preferentially along the < 001 > direction through the bridges. Meanwhile, the Hg nanodroplets formed, moved rapidly on the ratchet surface with the velocity of several tens of nm/s and were finally evolved into bigger ones through the nanobridges with the relatively large gap of ~ 6 nm. Distinctly and surprisingly, mediated by the solid-liquid interface at nanoscale, the liquid Hg with the ink-like feature jetted in the liquid cells. Such ink-jetting behavior would occur multiple times with the intervals from several to several tens of seconds, which was modulated through the competition between the reductive electrons and the oxidative species derived from the radiolysis of liquid by the electron-beam. In-depth understanding of distinct nanodroplets dynamics at nanoscale solid-gas and solid-liquid interfaces offers a feasible approach of designing liquid metal-based nanocomplexes with regulatory interfacial, morphological and rheological functionalities.