In Situ TEM Imaging of Solution‐Phase Chemical Reactions Using 2D‐Heterostructure Mixing Cells

Abstract

Liquid‐phase transmission electron microscopy is used to study a wide range of chemical processes, where its unique combination of spatial and temporal resolution provides countless insights into nanoscale reaction dynamics. However, achieving sub‐nanometer resolution has proved difficult due to limitations in the current liquid cell designs. Here, a novel experimental platform for in situ mixing using a specially developed 2D heterostructure‐based liquid cell is presented. The technique facilitates in situ atomic resolution imaging and elemental analysis, with mixing achieved within the immediate viewing area via controllable nanofracture of an atomically thin separation membrane. This novel technique is used to investigate the time evolution of calcium carbonate synthesis, from the earliest stages of nanodroplet precursors to crystalline calcite in a single experiment. The observations provide the first direct visual confirmation of the recently developed liquid‐liquid phase separation theory, while the technological advancements open an avenue for many other studies of early stage solution‐phase reactions of great interest for both the exploration of fundamental science and developing applications.

Crystal Nucleation and Growth of Inorganic Ionic Materials from Aqueous Solution: Selected Recent Developments, and Implications

“…[15] Also, recent LP-TEM work that introduced a novel technique for mixing solutions inside of the microscope, allowed capturing the ripening process of dense liquid CaCO 3 droplets formed upon spinodal decomposition, toward their binodal composition. [73] The observations appear to be in line with previous seminal work on the growth of ACC formed upon spinodal decomposition, where a monomer addition mechanism was found, [74] albeit no clear statement about the nature of the monomers was previously possible, and it seems now clear that they correspond to clusters rather than single ions. LP-TEM approaches can be extended to nucleation and growth of CaCO 3 in an immobilized matrix of poly(styrene sulfonate) as interacting polymer and ion sponge, demonstrating that the technique can also be applied to hybrid systems.…”

Solvent-mediated isotope effects strongly influence the early stages of calcium carbonate formation: exploring D2O vs. H2O in a combined computational and experimental approach

“…IAP spinodal agrees with the commonly accepted value of the solubility of (disordered) ACC 56 that is typically precipitated from high levels of supersaturation. Indeed, according to the PNC pathway, the as-formed liquid intermediates dehydrate towards the formation of solid ACC, as observed in situ recently, 57,58 thus transferring structural characteristics from the PNCs, over the liquid intermediates, to the initial amorphous solids. The solid ACCs later transform into crystals, at which stage different mechanisms may operate.…”

Unveiling the Dynamic Oxidative Etching Mechanisms of Nanostructured Metals/Metallic Oxides in Liquid Media Through In Situ Transmission Electron Microscopy

“…Though plenty of advancements have been achieved, the practical application of oxide etching is still facing several key challenges, and thus further opportunities associated with the technique are arising to solve these issues as displayed in Figure . [ 91–98 ]…”

“…Though plenty of advancements have been achieved, the practical application of oxide etching is still facing several key challenges, and thus further opportunities associated with the technique are arising to solve these issues as displayed in Figure 8. [91][92][93][94][95][96][97][98] The electron beam effect is one of the major challenges. [99,100] First, atomic displacement and sputtering are derived from the high-energy electron scattering.…”