Guanidinium nonaflate as a solid-state proton conductor

Guanidinium nonaflate, a novel pure protic organic ionic plastic crystal (POIPC) with an elegant symmetrical cation, is discovered to be a new solid-state proton conductor.</p

Liquid Metal Salts for electrodeposition and electrochemical nanoparticle synthesis

Ionic liquids are interesting electrolytes for electrochemical applications due to their wide liquidus range and wide electrochemical window, allowing metals to be electrodeposited from them that cannot be deposited from aqueous solutions. However, solubilities for many metals are low in ionic liquids, especially ionic liquids with weakly coordinating anions. Moreover, viscosities of ionic liquids are significantly higher than those of aqueous solutions. Therefore, liquid metal salts were developed. Liquid metal salts are ionic liquids in which a redox-active metal is incorporated into the cation of the ionic liquid. This way, very high metal concentrations are obtained. Liquid metal salts are excellent electrolytes for the electrodeposition of metals. Because the metal is incorporated into the cation, it will electromigrate towards the cathode during deposition, allowing a better mass transport to counteract the higher viscosity of the ionic liquid. Since the cathodic reaction is the deposition of metal, there are no issues with the cathodic decomposition of the ionic liquid components. In this work, the concept of liquid metal salts was further expanded to silver(I), nickel(II), manganese(II) and cobalt(II) compounds. Except for silver(I), which is two-coordinate, all compounds consist of a metal(II) cation that is octahedrally coordinated by six ligands. A range of different ligands is used in order to lower the melting point of the compounds. Several different N-alkylimidazoles were considered as ligands, but also common organic solvents such as dimethylsulfoxide, diglyme and triglyme and pyridine-N-oxide were used. The alkyl side chain on the N-alkylimidazole ligands was varied in length from methyl to dodecyl. The different counter anions that were used are bis(trifluoromethanesulfonyl)imide (bistriflimide), trifluoromethanesulfonate (triflate), methanesulfonate (mesylate) and nitrate. All newly synthesized liquid metal salts were characterized by CHN analysis, FTIR, DSC, TGA, viscosity measurements and, if good quality single crystals were obtained, single crystal X-ray diffraction was performed. Not only the chemical synthesis and characterization was performed, the compounds with the lowest melting points were tested for the electrodeposition of silver, nickel, manganese and cobalt. In all cases, reduction of the metal cations occurred without the presence of a limiting current during cyclic voltammetry experiments. This means that the system is never diffusion controlled, indicating a high mobility of the metal cation during electrodeposition. The original goal of the research was to build a library of several liquid metal salts using different metals, ligands and anions, and to test the compounds with the lowest melting points for electrodeposition. It was found however that for certain six-coordinate metal cations, no deposits were obtained but electrochemical metal nanoparticle synthesis was observed, as was evidenced by transmission electron microscopy measurements. This interesting observation was not observed for every liquid metal salt, but only occured when a certain ligand-anion combination was used. This was further investigated and a mechanism for the nanoparticle formation from nickel(II), manganese(II) and cobalt(II) liquid metal salts was formulated.status: publishe

Liquid Cobalt Salts as Non-Volatile Electrolytes for High Current Density Electrodeposition of Cobalt and Electrochemical Synthesis of Cobalt Nanoparticles

Oral presentation by Pieter Geysensstatus: publishe

Electrodeposition of indium from non-aqueous electrolytes

The electrochemical behaviour and deposition of indium in electrolytes composed of 0.4 mol dm-3 In(Tf2N)3 and 0.4 mol dm-3 InCl3 in the solvents 1,2-dimethoxyethane and poly(ethylene glycol) (average molecular mass of 0.400 kg mol-1, PEG400) was investigated. Indium(i) was identified as the intermediate species that disproportionated to indium(iii) and indium(0) nanoparticles. The presence of nanoparticles was verified by TEM analysis. SEM analysis showed that deposits obtained at room temperature from 1,2-dimethoxyethane were rough, while spherical structures were formed in PEG400 at 160 °C.status: publishe

Manganese-containing ionic liquids: synthesis, crystal structures and electrodeposition of manganese films and nanoparticles

Manganese(II)-containing ionic liquids were synthesized, in which the manganese atoms are coordinated by glymes (diglyme, triglyme, tetraglyme), pyridine-N-oxide, dimethylsulfoxide or N-alkylimidazoles (N-methylimidazole, N-butylimidazole and N-hexylimidazole). As anion, bis(trifluoromethanesulfonyl) imide (bistriflimide, Tf2N−), trifluoromethanesulfonate (triflate, OTf−) or methanesulfonate (mesylate, OMs−) were used. The compounds were characterized by CHN analysis, FTIR, DSC and single-crystal X-ray diffraction measurements. All manganese atoms were six-coordinate. It was found that the glymetype ligands were replaced by atmospheric water upon leaving the crystals open to the air for several days. The crystal structures of seven compounds were described in detail and the compounds with the lowest melting temperatures were tested as electrolytes for the electrodeposition of manganese (thin) films. An irreversible reduction wave from Mn(II) to Mn(0) and granular manganese deposits were observed for all compounds, except for liquid manganese salts with N-alkylimidazole ligands and bistriflimide anions, where the electrochemical formation of manganese nanoparticles was observed instead of the deposition of a manganese layer. However, for compounds with the same cation but with a triflate or methanesulfonate anion, manganese metal deposits were obtained, indicating that the nature of the anion has an important effect on the electrochemical properties of liquid metal salts.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information related_data: Crystal Structure Data identifier: Luc Van Meervelt (ORCID) identifier: Koen Binnemans (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal history: Received 19 December 2016; Accepted 23 January 2017; Accepted Manuscript published 24 January 2017; Advance Article published 1 February 2017; Version of Record published 21 February 2017status: publishe

Silver-containing ionic liquids for high rate electrodeposition

Poster presentation by Neil Brooksstatus: publishe

Electrodeposition of thick palladium coatings from a palladium(II)-containing ionic liquid

The first palladium-containing Liquid Metal Salts (LMS) are presented and shown to be suitable electrolytes for the electrodeposition of palladium. The homoleptic LMS of formula [Pd(MeIm)4][Tf2N]2 or [Pd(EtIm)4][Tf2N]2 (MeIm = N-methylimidazole, EtIm = N-ethylimidazole) have higher melting points than the heteroleptic [Pd(MeIm)2(EtIm)2][Tf2N]2, which is proved to be the most promising electrolyte. The deposition reaction in these LMS was found to be irreversible but smooth and dense palladium layers can be deposited that are crack-free up to a thickness of 10 microns.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information related_data: Crystal Structure Data copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available after a 12 month embargo period history: Received 28 May 2014; Accepted 14 July 2014; Accepted Manuscript published 14 July 2014; Advance Article published 23 July 2014; Version of Record published 7 August 2014status: publishe

High current density electrodeposition of silver from silver-containing liquid metal salts with pyridine-N-oxide ligands

New cationic silver-containing ionic liquids were synthesized and used as non-aqueous electrolytes for the electrodeposition of silver layers. In the liquid state of these ionic liquids, a silver (I) cation is coordinated by pyridine-N-oxide (py-O) ligands in a 1 : 3 metal-to-ligand ratio, although in some cases a different stoichiometry of the silver center crystallized out. As anions, bis(trifluoromethanesulfonyl)imide (Tf₂N), trifluoromethanesulfonate (OTf), methanesulfonate (OMs) and nitrate were used, yielding compounds with the formulae [Ag(py-O)₃][Tf₂N], [Ag(py-O)₃][OTf], [Ag(py-O)₃][OMs] and [Ag(py-O)₃][NO₃], respectively. The compounds were characterized by CHN analysis, FTIR, NMR, DSC, TGA and the electrodeposition of silver was investigated by cyclic voltammetry, linear potential scans, scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). With the exception of [Ag(py-O)₃][Tf₂N], which melts at 108 °C, all the silver(I) compounds have a melting point below 80 °C and were tested as electrolytes for silver electrodeposition. Interestingly, very high current densities were observed at a potential of −0.5 V vs. Ag/Ag⁺ for the compounds with fluorine-free anions, i.e. [Ag(py-O)₂][NO₃] (current density of −10 A dm¯²) and [Ag(py-O)₃][OMs] (−6.5 A dm¯²). The maximum current density of the compound with the fluorinated anion trifluoromethanesulfonate, [Ag(py-O)₃][OTf], was much lower: −2.5 A dm¯² at −0.5 V vs. Ag/Ag⁺. Addition of an excess of ligand to [Ag(py-O)₃][OTf] resulted in the formation of the room-temperature ionic liquid [Ag(py-O)₆][OTf]. A current density of −5 A dm¯² was observed at −0.5 V vs. Ag/Ag⁺ for this low viscous silver salt. The crystal structures of several silver complexes could be determined by X-ray diffraction, and it was found that several of them had a stoichiometry different from the 1 : 3 metal-to-ligand ratio used in their synthesis. This indicates that the compounds form crystals with a composition different from that of the molten state. The electrochemical properties were measured in the liquid state, where the metal-to-ligand ratio was 1 : 3. Single crystal X-ray diffraction measurements showed that silver(I) is six coordinate in [Ag(py-O)₃][Tf₂N] and [Ag(py-O)₃][OTf], while it is five coordinate in the other complexes. In [Ag₃(py-O)₈][OTf]₃, there are two different coordination environments for silver ions: six coordinate central silver ions and five coordinate for the outer silver ions. In some of the silver(I) complexes, silver–silver interactions were observed in the solid state.Poster presentation by Jeroen Sniekersstatus: publishe