Giant Radiolytic Dissolution Rates of Aqueous Ceria Observed In- Situ by Liquid-Cell TEM

Muhammad Sajid, Ali Asghar, Beverley J. Inkson, Günter Möbus, 2017
Poseidon Select TEM holder tip
Image courtesy of ChemPhysChem

Abstract

The dynamics of cerium oxide nanoparticle aqueous corrosion are revealed in situ. We use innovative liquid-cell transmission electron microscopy (TEM) combined with deliberate high-intensity electron-beam irradiation of nanoparticle suspensions. This enables life video-recording of materials reactions in liquid, with nm resolution. We introduce image quantification to measure detailed rates of dissolution as a function of time and particle size to be compared with literature data. Giant dissolution rates, exceeding any previous reports for chemical dissolution rates at room temperature by many orders of magnitude, are discovered. The reasons for this accelerated dissolution are outlined, including the importance of the radiolysis of water preceding the ceria attack. Electron–water interaction generates radicals, ions, and hydrated electrons, which assist in hydration and reductive dissolution of oxide minerals. The presented methodology has the potential to become a novel accelerated testing procedure to compare multiple nanoscale materials for relative aqueous durability. The ceria–water system is of crucial importance for the fields of catalysis, abrasive polishing, environmental remediation, and as simulant for actinide oxide behaviour in contact with liquid for nuclear engineering.

 

Impact Statement

The dissolution rates of cerium oxide nanoparticles observed in situ, using LC-TEM are over five orders of magnitude larger than conventionally measured dissolution rates, due to the radiolytic species formed by the electron beam.