Ionic liquids versus ionic liquid-based surfactants in dispersive liquid–liquid microextraction for determining copper in water by flame atomic absorption spectrometry

International audienc

Advanced design of a X-ray Absorption Spectroscopy setup for measuring transition metals speciation in molten carbonates, hydroxides and hydrogenosulfates

International audienceBattery recycling is currently becoming a crucial issue. One possible treatment path involves the use of molten salts. Mechanistic understanding of the underlying processes requires being able to analyze in-situ speciation in the molten salts at various temperatures. This can be advantageously achieved using X-ray absorption spectroscopy, the use of Quick-EXAFS facilities being particularly appropriate. Consequently, this paper presents the design and development of a new setup allowing to carry out Quick-EXAFS experiments in molten oxidizing salts at high temperature. We describe the different components of the cell and the performances of the heating device. We illustrate the capabilities of the setup by analyzing the temperature evolution of Co speciation upon dissolution of LiCoO 2 , a typical battery electrode material, in molten carbonates, hydroxides and hydrogenosulphates

Structural and Morphological Description of Sn/SnO x Core–Shell Nanoparticles Synthesized and Isolated from Ionic Liquid

The potential application of high capacity Sn-based electrode materials for energy storage, particularly in rechargeable batteries, has led to extensive research activities. In this scope, the development of an innovative synthesis route allowing to downsize particles to the nanoscale is of particular interest owing to the ability of such nanomaterial to better accommodate volume changes upon electrochemical reactions. Here, we report on the use of room temperature ionic liquid (i.e., [EMIm+][TFSI–]) as solvent, template, and stabilizer for Sn-based nanoparticles. In such a media, we observed, using Cryo-TEM, that pure Sn nanoparticles can be stabilized. Further washing steps are, however, mandatory to remove residual ionic liquid. It is shown that the washing steps are accompanied by the partial oxidation of the surface, leading to a core–shell structured Sn/SnOx composite. To understand the structural features of such a complex architecture, HRTEM, Mössbauer spectroscopy, and the pair distribution function were employed to reveal a crystallized β-Sn core and a SnO and SnO2 amorphous shell. The proportion of oxidized phases increases with the final washing step with water, which appeared necessary to remove not only salts but also the final surface impurities made of the cationic moieties of the ionic liquid. This work highlights the strong oxidation reactivity of Sn-based nanoparticles, which needs to be taken into account when evaluating their electrochemical properties