Liquid Metal Salts Research Articles

Integration of Electrochemical Sensing and Machine Learning to Detect Tuberculosis via Methyl Nicotinate in Patient Breath.

Tuberculosis (TB) remains a significant global health issue; making early, accurate, and inexpensive point-of-care detection critical for effective treatment. This paper presents a clinical demonstration of an electrochemical sensor that detects methyl-nicotinate (MN), a volatile organic biomarker associated with active pulmonary tuberculosis. The sensor was initially tested on a patient cohort comprised of 57 adults in Kampala, Uganda, of whom 42 were microbiologically confirmed TB-positive and 15 TB-negative. The sensor employed a copper(II) liquid metal salt solution with a square wave voltammetry method tailored for MN detection using commercially available screen-printed electrodes. An exploratory machine learning analysis was performed using XGBOOST. Utilizing this approach, the sensor was 78% accurate with 71% sensitivity and 100% specificity. These initial results suggest the sensing methodology is effective in identifying TB from complex breath samples, providing a promising tool for non-invasive and rapid TB detection in clinical settings.

A simulation study of steric effects on the anodic dissolution at high current densities

AbstractElectrochemical machining (ECM) and electropolishing are examples of anodic dissolution used in a wide variety of applications. Proper simulations of ECM require the establishment of a so‐called gel layer of liquid metal salt, responsible for the depletion of water close to the surface such that the oxygen evolution is reduced. However, this effect is neglected in many simulation efforts, although it is significant to improve the accuracy of the machining process. Some authors consider this effect by an engineered “water‐repelling” function that depends on the local metal ion concentration. As an alternative, we discuss the theoretical description and the implementation of modified Poisson–Nernst–Planck equations taking into account expressions in which each ion has its own maximum concentration and corresponding steric limit. We investigate a basic system of water, sodium chloride, and iron ions. Simulations pending on the local metal ion concentration for current densities show that the modified model works; steric effects become important for large current densities and the formation of a resistive gel layer is responsible for the reduction of water at the electrode. We observe that the electrostatic potential resulting from space charge effects is not affected by implementing the different species sizes. Further research is needed to explore the applicability of industrial simulation tools.

One-Pot Deconstruction and Conversion of Lignocellulose Into Reducing Sugars by Pyridinium-Based Ionic Liquid-Metal Salt System.

Constantly decreasing fossil resources and exceeding energy demands are the most alarming concerns nowadays. The only way out is to develop efficient, safe, and economical biomass processing protocols that can lead toward biofuels and fine chemicals. This research is one of such consequences involving the deconstruction and conversion of wheat straw carbohydrate constituents into reducing sugars via one-pot reaction promoted by Lewis acidic pyridinium-based ionic liquids (PyILs) mixed with different metal salts (MCl). Various parameters such as the type of metal salt, loading amount of metal salt, time, temperature, particle size of biomass, and water content which affect the deconstruction of wheat straw have been evaluated and optimized. Among the studied ionic liquid (IL) and metal salt systems, the best results were obtained with [BMPy]+. The dinitrosalicylic acid (DNS) assay was used to determine the percentage of total reducing sugars (TRS) generated during treatment of wheat straw. The deconstructed wheat straw was characterized with various analytical tools, that is, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) analyses. The IL–metal salt system was recycled for subsequent treatment of wheat straw. Statistical parameters were calculated from analysis of variance (ANOVA) at the 0.05 level of confidence.

Towards an all-copper redox flow battery based on a copper-containing ionic liquid.

The first redox flow battery (RFB), based on the all-copper liquid metal salt [Cu(MeCN)4][Tf2N], is presented. Liquid metal salts (LMS) are a new type of ionic liquid that functions both as solvent and electrolyte. Non-aqueous electrolytes have advantages over water-based solutions, such as a larger electrochemical window and large thermal stability. The proof-of-concept is given that LMSs can be used as the electrolyte in RFBs. The main advantage of [Cu(MeCN)4][Tf2N] is the high copper concentration, and thus high charge and energy densities of 300 kC l(-1) and 75 W h l(-1) respectively, since the copper(i) ions form an integral part of the electrolyte. A Coulombic efficiency up to 85% could be reached.

Liquid Nickel Salts: Synthesis, Crystal Structure Determination, and Electrochemical Synthesis of Nickel Nanoparticles.

New nickel-containing ionic liquids were synthesized, characterized and their electrochemistry was investigated. In addition, a mechanism for the electrochemical synthesis of nanoparticles from these compounds is proposed. In these so-called liquid metal salts, the nickel(II) cation is octahedrally coordinated by six N-alkylimidazole ligands. The different counter anions that were used are bis(trifluoromethanesulfonyl)imide (Tf2 N(-) ), trifluoromethanesulfonate (OTf(-) ) and methanesulfonate (OMs(-) ). Several different N-alkylimidazoles were considered, with the alkyl sidechain ranging in length from methyl to dodecyl. The newly synthesized liquid metal salts were characterized by CHN analysis, FTIR, DSC, TGA and viscosity measurements. An odd-even effect was observed for the melting temperatures and viscosities of the ionic liquids, with the complexes with an even number of carbon atoms in the alkyl chain of the imidazole having a higher melting temperature and a lower viscosity than the complexes with an odd number of carbons. The crystal structures of several of the nickel(II) complexes that are not liquid at room temperature were determined. The electrochemistry of the compounds with the lowest viscosities was investigated. The nickel(II) cation could be reduced but surprisingly no nickel deposits were obtained on the electrode. Instead, nickel nanoparticles were formed at 100 % selectivity, as confirmed by TEM. The magnetic properties of these nanoparticles were investigated by SQUID measurements.

Electrodeposition from Liquid Metal Salts

Ionic liquids are ideal for performing electrochemical reactions which cannot be carried out in aqueous solutions, due to their wide electrochemical window, intrinsic electrical conductivity and large liquidus range. One drawback is the limited solubility of simple inorganic metal salts, such as chlorides and sulfates. The lack of solubility leads to a correspondingly low limiting current density. This disadvantage can be circumvented by making the metal ion a part of the ionic liquid in a so-called Liquid Metal Salt. A general formula is e.g. [M(L)x][A], with M a metal ion, L a neutral ligand and A a counter anion. By making the metal ion a structural part of the ionic liquid, the concentration of metal ions can be as high as 3 mol dm-3 without the need to add a salt as metal source. Hence, even at 25 A dm-2 which is a large current in unstirred solutions, no sign of the decomposition of the ligand L or anion A could be detected in the metal deposits. These high current densities are explained by the fact that the electrochemical experiments are performed in a pure ionic liquid that acts as both the supporting electrolyte and the electrochemically active species, which is therefore present in a high concentration. Additionally, these Liquid Metal Salts do not have a cathodic decomposition potential since their cathodic limit is the metal reduction. The use of solution additives, such as thiourea or benzotriazole, was investigated by Raman spectroscopy for their influence on the deposit morphology. So far we have synthesized and tested Liquid Metal Salts based on copper, silver, lithium, zinc, cobalt, nickel and palladium. Investigated ligands are (o.a.) acetonitrile, alkylimidazoles, py-N-O and amines. These cations were combined with anions such as bistriflimide, triflate or nitrate. These liquid metal salts show great promise in a wide variety of electrochemical applications.

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.

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)3][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.

Silver‐Containing Ionic Liquids with Alkylamine Ligands

AbstractThe synthesis, structure and electrochemical properties of several silver‐containing liquid metal salts have been investigated. These ionic liquids comprise of a silver‐containing cation with a silver centre coordinated by two or more alkylamine ligands and a bis(trifluoromethylsulfonyl)imide (Tf2N) anion. With the monodentate amines tert‐butylamine (tBuAm), iso‐butylamine (iso‐BuAm), sec‐butylamine (sec‐BuAm), 2‐ethylhexylamine (2‐EtHexAm), di(2‐ethylhexyl)amine and piperidine (pip), compounds with the formula [Ag(L)2][Tf2N] are formed, several of which are room‐temperature ionic liquids and all melt at or below 100 °C. In the case of [Ag(L)2][Tf2N] (L=tBuAm, iso‐BuAm and pip), single‐crystal X‐ray diffraction shows that, in the solid state, the silver centres are two‐fold coordinated by two amine ligands and the anion and cation exist as separated ion pairs. With ethylenediamine (en), two different compounds were formed, depending on the silver‐to‐ligand ratio and their structures were elucidated by X‐ray diffraction. [Ag(en)][Tf2N] has a very high melting point and is polymeric in the solid state, with en ligands coordinated to different silver(I) centres, creating one‐dimensional chains. [Ag(en)2][Tf2N], on the other hand, is a room‐temperature ionic liquid, with four‐coordinate silver(I) centres, but is actually polymeric in the solid state. The electrodeposition behaviour of [Ag(2‐EtHexAm)2][Tf2N] and [Ag(en)2][Tf2N] was investigated both at room temperature and at 90 °C and it was possible to achieve very high current densities in unstirred solutions and to electrodeposit closed, crack‐free, silver coatings. A crystal of [Ag2(en)Cl2] was obtained from a solution of [Ag(en)][Tf2N] in deuterochloroform and its structure is described.

High current density electrodeposition from silver complex ionic liquids

Liquid metal salts are electrolytes with the highest possible metal concentration for electrodeposition, because the metal ion is an integral part of the solvent. This paper introduces the new ionic silver complexes [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)], [Ag(MeCN)][Tf(2)N] and [Ag(EtIm)(2)][Tf(2)N], where MeCN stands for acetonitrile, EtIm for 1-ethylimidazole and Tf(2)N is bis(trifluoromethylsulfonyl)imide. These complexes have been characterized by differential scanning calorimetry, single crystal X-ray crystallography, thermogravimetrical analysis, Raman spectroscopy and cyclic voltammetry. [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)] is a room temperature ionic liquid. Smooth silver layers of good quality could be deposited from it, at current densities of up to 25 A dm(-2) in unstirred solutions. [Ag(EtIm)(2)][Tf(2)N] melts at 65 °C and can be used as an electrolyte for silver deposition above this temperature. [Ag(MeCN)][Tf(2)N] has a melting point that is too high to be useful in electrodeposition. Addition of thiourea or 1H-benzotriazole to the electrolyte decreased the surface roughness of the silver coatings. The morphology of the metal layers was investigated by atomic force microscopy (AFM). Adsorption of 1H-benzotriazole on the silver metal surface has been proven by Raman spectroscopy. This work shows the usefulness of additives in improving the quality of metal films electrodeposited from ionic liquids.

Liquid Metal Salts: Ionic Liquids for High Current Density Electroplating of Copper and Silver

not Available.

ON THE ORIGIN OF PHASE SEPARATION IN LIQUID METAL-SALT MIXTURES

The thermodynamic properties of liquid metal salt mixtures are studied with the help of a model in which the metallic and halogenic constituents interact with each other via an electronically screened Coulomb potential. It is shown that the phase separation of liquid metal salt mixtures is a direct consequence of the metal-nonmetal transition that occurs in these systems as a function of concentration.