Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

Abstract

We have designed and fabricated a TEM (transmission electron microscopy) liquid cell with hundreds of graphene nanocapsules arranged in a stack of two Si3N4–x membranes. These graphene nanocapsules are formed on arrays of nanoholes patterned on the Si3N4–x membrane by focused ion beam milling, allowing for better resolution than for the conventional graphene liquid cells, which enables the observation of light elements, such as atomic structures of silicon. We suggest that multiple nanocapsules provide opportunities for consecutive imaging under the same conditions in a single liquid cell. The use of single-crystal graphene windows offers an excellent signal-to-noise ratio and high spatial resolution. The motion of silicon nanoparticles (a low atomic number (Z) material) interacting with nanobubbles was observed, and analyzed, in detail. Our approach will help advance liquid-phase TEM observations by providing a straightforward method to encapsulate liquid between monolayers of various 2-dimensional materials.

Graphene Electrode for Studying CO2 Electroreduction Nanocatalysts under Realistic Conditions in Microcells

“…[12] In both single-crystal and polycrystal states, graphene has a Young's modulus value up to 3 times greater than the SiN x membranes. [13] Hence, graphene cells of different generations are reported to exhibit less bulging and enable thinner liquid layers, allowing high-resolution imaging of materials in liquid media. [7,14] Furthermore, the development of MEMS-based graphene chips has enabled precise control over the liquid environment and thickness, in contrast to the initial design of graphene cells using a veil-type configuration where the liquid is trapped into pockets formed via Van der Waals interactions of two graphene sheets.…”