Goethite Mineral Dissolution to Probe the Chemistry of Radiolytic Water in Liquid‐Phase Transmission Electron Microscopy

Abstract

Liquid‐Phase Transmission Electron Microscopy (LP‐TEM) enables in situ observations of the dynamic behavior of materials in liquids at high spatial and temporal resolution. During LP‐TEM, incident electrons decompose water molecules into highly reactive species. Consequently, the chemistry of the irradiated aqueous solution is strongly altered, impacting the reactions to be observed. However, the short lifetime of these reactive species prevent their direct study. Here, the morphological changes of goethite during its dissolution are used as a marker system to evaluate the influence of radiation on the changes in solution chemistry. At low electron flux density, the morphological changes are equivalent to those observed under bulk acidic conditions, but the rate of dissolution is higher. On the contrary, at higher electron fluxes, the morphological evolution does not correspond to a unique acidic dissolution process. Combined with kinetic simulations of the steady state concentrations of generated reactive species in the aqueous medium, the results provide a unique insight into the redox and acidity interplay during radiation induced chemical changes in LP‐TEM. The results not only reveal beam‐induced radiation chemistry via a nanoparticle indicator, but also open up new perspectives in the study of the dissolution process in industrial or natural settings.

Precision of Radiation Chemistry Networks: Playing Jenga with Kinetic Models for Liquid-Phase Electron Microscopy

“…For pure water, this denotes H 2 , H 2 O 2 , and O 2 . Moreover, we track the parameters defining the acidity under irradiation, namely the radiolytic acidity π* and the radiolytic ion product K W * . , Those are defined by π * = lg ( [ H + ] [ OH − ] ) K normalW * = false( [ H + ] · [ OH − ] false) irradiated Thus, we implicitly track the concentrations of H + and OH – , as well. We regard any of these parameters as reasonably unchanged if the relative change between the outcome of the complete, initial model and the model with the reduced reaction set remains within a 5% margin.…”

“…Here, access is granted by employing X-rays or high energy electrons. In particular liquid-phase transmission electron microscopy (LP-TEM) enables unique insights into multifarious fields of applied research, such as nanochemistry, , energy conversion, or geoscience, , down to atomic resolution . Yet, accurate interpretation of such studies is nontrivial and often relies on simulations.…”

Characterization of Nanomaterials Using In Situ Liquid-Cell Transmission Electron Microscopy: A Review

“…There have been many similar reports on various metals, − ,− oxides, − and alloys − ,− in recent years. Dynamic imaging observation of corroded nanoscale microstructure features in liquid-cell TEM has exciting application prospects.…”

Emerging transmission electron microscopy solutions for electrocatalysts: from synthesis to deactivation

“…On the one hand, the exact synthesis may not be reproduced in LC-TEM where permitted solutions and concentrations are limited for experimental safety. On the other hand, introducing electrons for imaging inevitably leads to radiolysis of water and thus generates various species, such as e aq − , H˙, HO˙, HO 2 ˙, OH − , H 3 O + , H 2 and H 2 O 2 , 51,87–91 drastically altering the exact reaction conditions in the condensed space of a liquid cell. Therefore, the difference between in situ conditions and operando conditions has to be taken into account in the interpretation of LC-TEM results.…”