Search results for "ionic"
showing 10 items of 2016 documents
Applicability of a Polymerized Ionic Liquid/Carbon Nanoparticle Composite Electrolyte to Reductive Cyclization and Dimerization Reactions
2016
Abstract Recently, a reusable polymerized ionic liquid/carbon nanoparticle composite electrolyte was developed and effectively applied to a variety of oxidative transformations. The efficient recovery of the composite material and its application in subsequent electroorganic conversions without sacrificing yield adds to the sustainability of the protocol. Herein, we describe our efforts to expand the operational window of the composite electrolyte to include cathodically initiated processes occurring at potentials up to −2.6 V. The results indicate that the composite electrolyte is applicable to reductive processes, but the scope of transformations appears to be limited.
An electrochemical process to prepare and recycle biobased ionic liquids
2019
This manuscript describes the first electrosynthesis of biobased ionic liquids from L-valine, oxalic acid and glyoxal, which is energy-efficient, does not emit toxic waste and avoids the formation of inorganic waste. These ionic liquids were then used in the development of our electro-recycling process. While their recycling yields are still moderated due to recombination and disproportionation reactions, this unprecedented recycling technology is very promising in terms of environmental and economic gains. Indeed, it has a high energy efficiency, requires low cost equipment, allows a strong decrease of the price of such ionic solvents, limits the use of non-renewable resources and solves t…
The behaviour of zirconium and hafnium during water-rock interaction
2018
Abstract Zr and Hf are two elements with same ionic charge and similar ionic size at a given coordination number. Despite the Zr/Hf ratio is quite constant in meteorites and lithospheric rocks, in natural waters can be either higher or lower compared to values of interacting minerals and rocks. Here, we reanalyze very recent published and present new data on continental and brine waters indicating that the Zr and Hf behavior is dependent on the properties of the authigenic phases formed during the water-rock interaction process. Our results show that water pH in the range between 1 and 9 and water ionic strength in the range between 0.001 and 4 mol kg−1 are responsible for the change of the…
Dispersion and Stabilization of Exfoliated Graphene in Ionic Liquids.
2019
The liquid-phase exfoliation of graphite is one of the most promising methods to increase production and commercial availability of graphene. Because ionic liquids can be easily obtained with chosen molecular structures and tuneable physicochemical properties, they can be use as media to optimise the exfoliation of graphite. The under- standing of the interactions involved between graphite and various chemical functions in the solvent ions will be helpful to find liquids capable of dissociating and stabilising im- portant quantities of large graphene layers. After a step of sonication, as a mechanical precursor, samples of suspended exfoliated graphene in different ionic liquids have been c…
Preparation of conductive PDDA/(PEDOT:PSS) multilayer thin film: influence of polyelectrolyte solution composition.
2014
Abstract Self-assembled multilayer films made of PEDOT:PSS poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and PDDA poly(diallyldimethylammonium chloride) were prepared using layer-by-layer method. In order to modify the growth regime of the multilayer, to fabricate an electrical conductive film and to control its thickness, the effects of pH, type of electrolyte, ionic strength and polyelectrolyte concentration were investigated. Optical reflectometry measurements show that the pH of the solutions has no effect on the film growth while the adsorbed amount increases more rapidly when BaCl2 is used instead of NaCl as electrolyte. An increase in the ionic strength (with NaCl) induces…
Proton sponge lead halides containing 1D polyoctahedral chains
2021
Hybrid one-dimensional lead halides, containing the protonated 1,8-bis(dimethylamino)naphthalene moiety (C14H19N2, monoprotonated "proton sponge"), were prepared by simple one-pot methods and investigated in terms of crystal structure, morphology, thermal stability and electronic properties. The as-precipitated (C14H19N2)PbBr3 and (C14H19N2)PbI3 species are isostructural and crystallize in the orthorhombic Pbca space group, resulting in 1D crystal phases with ([PbX3](-))(infinity) chains (built by face-sharing [PbX6] octahedra; X = Br, I), among which the (C14H19N2)(+) cations are inserted. The two compounds display complete miscibility in the solid state: both (C14H19N2)PbI2Br and (C14H19N…
Microstructured electrodeposited polypyrrole–phthalocyanine hybrid material, from morphology to ammonia sensing
2012
Hybrid materials combining polypyrrole with ionic macrocycles as counterions are electrosynthesized at the surface of platinum interdigitated electrodes. The chemical composition of the hybrid films is characterized by infrared reflexion absorption spectroscopy (IRRAS) and glow discharge optical emission spectroscopy (GDOES) and their morphology is studied by a range of techniques such as optical topomicroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained films reveal to be more homogeneous, with smaller crystallites, compared to polypyrrole synthesized with small counterions. Finally, the films exhibit a higher sensitivity to ammonia, with a very good…
Influence of pressure on ultrasonic cavitation activity in room temperature ionic liquids: An electrochemical study
2019
Abstract This paper provides proofs of the respective contributions of dissolved gases and solvent vapor on cavitation activity in sonoreactors. This activity can be detected by electrochemistry because the fluctuating events measured at the electrode surface are only linked to physical effects of cavitation. As ionic liquids present very low volatilities, their vaporization is reduced, and cavitation bubbles only depend on the presence of gases. Then, cavitation activity may be trigged by reactor atmosphere control. Applying severe depression within an irradiated ionic liquid medium contributes to removing dissolved gases, thus quenching cavitation activity. A specific sonoelectrochemical …
Covalent bonding and the nature of band gaps in some half-Heusler compounds
2005
Half-Heusler compounds \textit{XYZ}, also called semi-Heusler compounds, crystallize in the MgAgAs structure, in the space group $F\bar43m$. We report a systematic examination of band gaps and the nature (covalent or ionic) of bonding in semiconducting 8- and 18- electron half-Heusler compounds through first-principles density functional calculations. We find the most appropriate description of these compounds from the viewpoint of electronic structures is one of a \textit{YZ} zinc blende lattice stuffed by the \textit{X} ion. Simple valence rules are obeyed for bonding in the 8-electron compound. For example, LiMgN can be written Li$^+$ + (MgN)$^-$, and (MgN)$^-$, which is isoelectronic wi…
Cesium-Induced Ionic Conduction through a Single Nanofluidic Pore Modified with Calixcrown Moieties
2017
[EN] We demonstrate experimentally and theoretically a nanofluidic device for the selective recognition of the cesium ion by exploiting host¿guest interactions inside confined geometry. For this purpose, a host molecule, i.e., the amine-terminated p-tert-butylcalix[4]arene-crown (tBuC[4]C¿NH2), is successfully synthesized and functionalized on the surface of a single conical nanopore fabricated in a poly(ethylene terephthalate) (PET) membrane through carbodiimide coupling chemistry. On exposure to the cesium cation, the t-BuC[4]C¿Cs+ complex is formed through host¿guest interaction, leading to the generation of positive fixed charges on the pore surface. The asymmetrical distribution of the…