Ethylammonium Nitrate Research Articles

Electrodeposition of Amorphous and Nanocrystalline Ni-Co Alloys of Controlled Composition from Protic Ionic Liquid and Their Use for the Hydrogen Evolution Reaction

In recent years, a growing interest has been paid in developing new and more efficient electrocatalysts for water splitting [1]. This study focuses on the synthesis of amorphous and nanocrystalline Ni-Co alloys through a one-step electrodeposition technique in pure ethylammonium nitrate (EAN), a protic ionic liquid. The use of ionic liquid prevents from the formation of oxide film during the electrodeposition of the metal [2]. However, only few studies involve protic ionic liquids and the use of EAN, in particular, the electrodeposition of Ni/Co-based materials is still scarce. In this work, the physicochemical properties of EAN with different concentrations of Ni2+ and Co2+ salts were investigated, along with the electrochemical behavior of these metal cations in the protic ionic liquid in an aerated atmosphere. Moreover, the redox reversibility of electrochemical systems involving Ni and Co ions were examined by cyclic voltammetry, revealing the formation of an oxide film or side-reactions in the presence of air during electrodeposition, showing the need to prepare these materials in an oxygen-free environment. The deposits have then been characterized by TEM (Figure 1). Nanocrystalline Ni-Co alloys with different atomic ratios were obtained depending on the deposition potential and ion concentrations. We showed that when a higher cathodic potential is applied (-1.3 V/Ag/Ag+), the amorphous Ni51.9Co48.1 alloy could be electrodeposited, instead of nanocrystalline alloys. The XRD and SEM analyses exhibited different morphologies and atomic structures of the synthesized alloys.The electrocatalytic properties of the synthesized materials were investigated towards the hydrogen evolution reaction (HER). The results showed that the addition of Co in Ni-based alloys could enhance the HER, and notably, amorphous Ni-Co alloys exhibited lower overpotential, indicating better reaction abilities and faster reaction rates. The deposited Ni-Co alloys on Cu board also demonstrated good stability during the recycle measurement. This study provides a new pathway for preparing nanocrystalline and amorphous Ni-Co alloys with different ratios using protic ionic liquid, which can have practical applications and good performances in electrocatalysis such as water splitting.[1] M. Zhao, K. Abe, S.-I. Yamaura, Y. Yamamoto, N. Asao, Chem. Mater. 2014(26) 1056-1061.[2] M. Asnavande, C. Zhao, Chem. Mater. 26 (2014) 1056-1061. ACS Sustain. Chem. Eng. 2017 5 (1) 85-89. Figure 1

Photochromic ionogel with a wide temperature range and fatigue resistance for high-resolution rewritable information record

Recently, photochromic hydrogels have received significant attention and hold substantial promise for rewritable information record. However, the intrinsic instability of hydrogels has restricted their applications. Herein, a photochromic ionogel aiming at extending service life for long-term use is presented by embedding photochromic ammonium molybdate tetrahydrate [(NH4)6Mo7O24·4H2O] (Mo7) in engineered double networks. Covalently cross-linked 2-hydroxyethyl acrylate (HEA) and self-assembled cationic cellulose (JR-400) constitute the networks, and a protic ionic liquid of ethylammonium nitrate (EAN) is immobilized therein. Such a design affords the ionogel comprehensive properties, including high optical transparency (>97%), good adhesion, anti-dehydration, wide operating temperature range (–60 to 150 °C) as well as the sensitive and stable UV-light responsiveness (within 30 s). Besides, the ionogel exhibits admirable mechanical properties of high toughness (over 180 kJ/m3), excellent resilience and a high fatigue threshold (over 1000 cycles with negligible hysteresis). The photochromic process is typically accomplished by photoreduction of Mo7, which is combined with network through electrostatic interaction with quaternized JR-400. The distinctive feature is that EAN serving as both proton donor and electron donor, plays a dominant role in coloration process and formation of charge-transfer complex. The photochromic mechanism which is less well understood in ionic liquid medium, has been revealed. Remarkably, the ionogel used as an information carrier exhibits outstanding stability in a wide operating temperature range. The superiorities of the photochromic ionogel including accurate information recording capacity and application in harsh environments have greatly boosted the high-quality information dissemination and expanded applications of photochromic soft materials.

NMR study of nitrate ionic liquids confined between micrometer-spaced plates

This review paper presents the results of a study conducted using nuclear magnetic resonance (NMR) methods to investigate the dynamic behaviour of ionic liquid-based compositions in micrometre-spaced confinement. Ethylammonium nitrate (EAN) and other ionic liquid (IL) systems with nitrate anion in glass or quartz spaced confinement demonstrate anomalous cation dynamics that differ from those observed in bulk and in nano-confinement. It was demonstrated that the principal axis of the nitrate anion exhibits preferential orientation to the surface, akin to that in liquid crystals. It was shown that the cation translational mobility reversibly changes during exposure to a static magnetic field. This phenomenon was interpreted as a result of intermolecular structure transformations occurring in the confined ILs. The mechanisms of these transformations were discussed.

On the molecular mechanisms of H2/N2 uptake in confined ionic liquids: A computational study

Classical molecular dynamics and hybrid grand canonical Monte Carlo/molecular dynamics simulations were combined to analyze the gas uptake mechanism of hydrogen and nitrogen molecules inside carbon nanotubes filled with an ionic liquid. Several nanotube diameters (from 6 Å to 12.24 Å) and two different ionic liquids (ethylammonium nitrate and 1-ethyl-3-methylimidazolium tetrafluoroborate) were considered to study their effect on the gas capture capacity and on the location of gas molecules within the nanotubes. The simulations showed that nitrogen absorption ability is, in general, greater than that of hydrogen, with the aprotic ionic liquid being more efficient for gas confinement. In addition, gas capture was observed to increase from a scarce 0.4% in bulk ionic liquids up to 8%-25% inside small nanotubes, and the maximum gas uptake was observed for those nanotubes that allow for a greater degree of conformational freedom of the ionic liquid. However, our calculations show that, whereas hydrogen storage is mainly governed by the amount of accessible free volume, for understanding that of nitrogen solvation energetics must be also considered. In all cases, gas molecules are absorbed in the ionic liquid-rich-region, but the interactions with the other components of the system favour their accommodation closer to the carbon wall than to the nanotube centre. Finally, single-particle dynamics of gas molecules was analyzed by means of the velocity autocorrelation functions and the vibrational density of states, which show a blue-shifting when increasing the radius of the nanotube.

In Situ Study on the Structural Evolution of Flexible Ionic Gel Sensors

With the development of society, the demand for smart coatings is increasing. The development of flexible strain sensors using block copolymer self-assembled ionic gel materials provides a promising method for promoting the development of smart coatings. The ionic liquid in the ionic part of the material is crucial for the performance of the sensor. In this study, the structural changes within FDA/dEAN (self-assembly of acrylated Pluronic F127 (F127-DA) in partially deuterated ethylammonium nitrate (dEAN)) triblock copolymer ionic gel during uniaxial tensile flow were characterized using an in situ SAXS technique. The results revealed that the characteristics of the responses of the ionic gel to strain resistance were intricately linked to the evolution of its microstructure during the tensile process. At low levels of strain, the face-centered cubic lattice arrangement of the micelles tended to remain unchanged. However, when subjected to higher strains, the molecular chains aligned along the stretching direction, resulting in a more ordered structure with reduced entropy. This alignment led to significant disruption in bridging structures within the material. Furthermore, this research explored the impact of the stretching rate on the relaxation process. It was observed that higher stretching rates led to decreases in the average relaxation time, indicating rate dependence in the microstructure’s behavior. These findings provide valuable insights into the behavior and performance of flexible strain sensors based on ionic gel materials in smart coatings.

Thermal Stability of Protic Ionic Liquids.

While protic ionic liquids (ILs) have found great success as solvents for a broad range of applications, little is known about their degradation when exposed to temperatures above ambient for extended periods of time. Here, we report the thermal stability of six protic ILs, namely, ethylammonium nitrate, ethylammonium formate, ethylammonium acetate, ethanolammonium nitrate, ethanolammonium formate, and ethanolammonium acetate. The effect of heating each ionic liquid to 60 °C for 1 h or 1 week (sealed or open to the atmosphere) was evaluated by considering the changes to water content, pH, mass, thermal phase transitions, and molecular structure after each treatment. Heating each of the six ILs when sealed led to measurable shifts in their water content and 10 wt % pH, but there was no significant change in their mass, thermal phase transitions according to differential scanning calorimetry (DSC), or molecular structure using proton nuclear magnetic resonance (1H NMR) spectra, indicating that the samples were largely unchanged. The samples that were heated open to the atmosphere also displayed no significant changes after 1 h but displayed significant changes after 1 week.

Ionogels based on protic ionic liquid - lithium salt mixtures

The effect of the addition of lithium nitrate on the liquid range and electrical conductivity of mixtures of a protic ionic liquid, ethylammonium nitrate (EAN) with LiNO3 is reported in this work. Moreover, changes in these properties upon confinement in silica-based matrices are also analysed and related to variations on the microstructure of the mixtures. Our results show that gelation of the mixtures induces amorphous behaviour in all the samples, but no significant changes in the thermal stability are detected. However, important differences on the electrical conductivity of the liquid and gel states of the mixtures were observed. While this magnitude decreases with the addition of salt in the liquid samples for all the temperatures it increases at low concentrations of LiNO3 up to a maximum in the gelled samples with the lowest concentration of added salt (0.1 mol of salt by kg of EAN). High resolution magic angle spinning (HRMAS) NMR shows that the addition of lithium nitrate increases the mobility (both rotational and translational motion) of the cation EA+ within the ionogel and the diffusion of the cation provides evidence of the presence of two different populations of the same molecules experiencing two distinct apparent diffusion coefficients (bi-exponential decay of magnetization in diffusion NMR experiments), while it is mono-exponential in the pure ionic liquid. The Li+ cation is shown to display a higher mobility (both rotational and translational motion) in the ionogel than in the neat ionic liquid. The frustration of the formation of solvation complexes due to the confinement is suspected to be behind this behaviour.

Lyotropic liquid crystal phases of monoolein in protic ionic liquids.

Monoolein-based liquid crystal phases are established media that are researched for various biological applications, including drug delivery. While water is the most common solvent for self-assembly, some ionic liquids (ILs) can support lipidic self-assembly. However, currently, there is limited knowledge of IL-lipid phase behavior in ILs. In this study, the lyotropic liquid crystal phase behavior of monoolein was investigated in six protic ILs known to support amphiphile self-assembly, namely ethylammonium nitrate, ethanolammonium nitrate, ethylammonium formate, ethanolammonium formate, ethylammonium acetate, and ethanolammonium acetate. These ILs were selected to identify specific ion effects on monoolein self-assembly, specifically increasing the alkyl chain length of the cation or anion, the presence of a hydroxyl group in the cation, and varying the anion. The lyotropic liquid crystal phases with 20-80 wt. % of monoolein were characterized over a temperature range from 25 to 65 °C using synchrotron small angle x-ray scattering and cross-polarized optical microscopy. These results were used to construct partial phase diagrams of monoolein in each of the six protic ILs, with inverse hexagonal, bicontinuous cubic, and lamellar phases observed. Protic ILs containing the ethylammonium cation led to monoolein forming lamellar and bicontinuous cubic phases, while those containing the ethanolammonium cation formed inverse hexagonal and bicontinuous cubic phases. Protic ILs containing formate and acetate anions favored bicontinuous cubic phases across a broader range of protic IL concentrations than those containing the nitrate anion.

Dispersions of magnetic nanoparticles in water/ionic liquid mixtures.

Nanoparticles (NPs) of iron oxide are dispersed in mixtures of water and ionic liquid, here ethylammonium nitrate (EAN), and the NP/NP and NP/solvent interactions are studied. They are analysed via small-angle X-ray scattering and dynamic light scattering coupled to forced Rayleigh scattering, from 22 °C to 80 °C. The NPs are well-dispersed as individual objects in the whole range of compositions and temperatures thanks to sufficient repulsion due to the organization of the solvents at the interface. The surface changes from hydrophilic to hydrophobic around a proportion of 50 vol% water : 50 vol% EAN, following the evolution of the bulk mixtures, which remain heterogeneous in the whole range of compositions.

(Invited) On the Inhibition Mechanism of an Alkylammonium Nitrate Ionic Liquid Family on Al Alloys: Electrochemical and XPS/in Situ PM-IRRAS Studies

AA2024 are high strength Al alloys widely used in the aerospace industry due to their excellent strength to weight ratio. However, their high susceptibility to localised corrosion, caused by the presence of intermetallic particles embedded in the Al matrix, requires the use of chromate-based surface treatment formulations1. Several alternatives have been explored in the last decades, such as vanadates, chromium (III) based conversion coatings, rare-earth inhibitors or more recently, lithium containing conversion coatings2. However, these alternatives are often not versatile (cannot be transposed to all alloy systems) or are not as cost effective as chromates. Ionic liquids (ILs), usually defined as salts with a melting point below 100°C, can be considered as promising corrosion inhibitors due to their low vapour pressure, chemical and thermal stability3. In addition, they can exhibit versatile inhibition properties associated with the quasi-infinite possible anion-cation combinations3–5. In previous work, the effect of an alkylammonium nitrate IL family, namely ethylammonium nitrate (EAN), propylammonium nitrate (PAN), and butylammonium nitrate (BAN) as potential corrosion inhibitors for an AA2024-T6 Al alloy was investigated6. Electrochemical tests such as potentiodynamic polarisation and electrochemical impedance spectroscopy were performed to identify the effect of the anion and cation on the anodic and cathodic kinetics. Herein, surface analysis was performed to rationalise the electrochemical results, particularly on the reactivity of NO3 - and R-NH3 + on the Cu-rich intermetallic particles. To this end, electrospray ionisation of EAN, BAN and NaNO3 was realised on Cu. The effect of the IL concentration and cation chain length, using PM-IRRAS (polarisation modulation -infrared reflection adsorption spectroscopy) was used to investigate molecule orientation and surface-molecule bonding as a function of surface coverage; The results provided new insights on the inhibition mechanism of this IL family. O. Gharbi, S. Thomas, C. Smith, and N. Birbilis, Npj Mater Degrad, 2, 12 (2018) http://www.nature.com/articles/s41529-018-0034-5.A. Kosari et al., Corros Sci, 190, 109651 (2021) https://doi.org/10.1016/j.corsci.2021.109651.C. Verma, E. E. Ebenso, and M. A. Quraishi, J Mol Liq, 233, 403–414 (2017) http://dx.doi.org/10.1016/j.molliq.2017.02.111.J. Sun, P. C. Howlett, D. R. MacFarlane, J. Lin, and M. Forsyth, Electrochim Acta, 54, 254–260 (2008).N. V. Likhanova et al., Corros Sci, 52, 2088–2097 (2010) http://dx.doi.org/10.1016/j.corsci.2010.02.030.A. Z. Benbouzid et al., Corrosion Communications, 9, 57–64 (2023).

H-bond network, interfacial tension and chain melting temperature govern phospholipid self-assembly in ionic liquids

HypothesisThe self-assembly structures and phase behaviour of phospholipids in protic ionic liquids (ILs) depend on intermolecular forces that can be controlled through changes in the size, polarity, and H-bond capacity of the solvent. ExperimentsThe structure and temperature stability of the self-assembled phases formed by four phospholipids in three ILs was determined by a combination of small- and wide-angle X-ray scattering (SAXS and WAXS) and small-angle neutron scattering (SANS). The phospholipids have identical phosphocholine head groups but different alkyl tail lengths and saturations (DOPC, POPC, DPPC and DSPC), while the ILs’ amphiphilicity, H–bond network density and polarity are varied between propylammonium nitrate (PAN) to ethylammonium nitrate (EAN) to ethanolammonium nitrate (EtAN). FindingsThe observed structures and phase behaviour of the lipids becomes more surfactant–like with decreasing average solvent polarity, H-bond network density and surface tension. In PAN, all the investigated phospholipids behave like surfactants in water. In EAN they exhibit anomalous phase sequences and unexpected transitions as a function of temperature, while EtAN supports structures that share characteristics with water and EAN. Structures formed are also sensitive to proximity to the lipid chain melting temperature.

Phase Behavior and Structure of Poloxamer Block Copolymers in Protic and Aprotic Ionic Liquids.

Ionic liquids are promising media for self-assembling block copolymers in applications such as energy storage. A robust design of block copolymer formulations in ionic liquids requires fundamental knowledge of their self-organization at the nanoscale. To this end, here, we focus on modeling two-component systems comprising a Poly(ethylene oxide)-poly (propylene oxide)-Poly(ethylene oxide) (PEO-PPO-PEO) block copolymer (Pluronic P105: EO37PO58EO37) and room temperature ionic liquids (RTILs): protic ethylammonium nitrate (EAN), aprotic ionic liquids (1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), or 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). Rich structural polymorphism was exhibited, including phases of micellar (sphere) cubic, hexagonal (cylinder), bicontinuous cubic, and lamellar (bilayer) lyotropic liquid crystalline (LLC) ordered structures in addition to solution regions. The characteristic scales of the structural lengths were obtained using small-angle X-ray scattering (SAXS) data analysis. On the basis of phase behavior and structure, the effects of the ionic liquid solvent on block copolymer organization were assessed and contrasted to those of molecular solvents, such as water and formamide.

Effect of Potential on the Nanostructure Dynamics of Ethylammonium Nitrate at a Graphite Electrode.

Video-rate atomic force microscopy (AFM) is used to study the near-surface nanostructure dynamics of the ionic liquid ethylammonium nitrate (EAN) at a highly oriented pyrolytic graphite (HOPG) electrode as a function of potential in real-time for the first time. The effects of varying the surface potential and adding 10wt% water on the nanostructure diffusion coefficient are probed. For both EAN and the 90wt% EAN-water mixture, disk-like features ≈9nm in diameter and 1nm in height form above the Stern layer at all potentials. The nanostructure diffusion coefficient increases with potential (from OCP -0.5V to OCP +0.5V) and with added water. Nanostructure dynamics depends on both the magnitude and direction of the potential change. Upon switching the potential from OCP -0.5V to OCP +0.5V, a substantial increase in the diffusion coefficients is observed, likely due to the absence of solvophobic interactions between the nitrate (NO3 - ) anions and the ethylammonium (EA+ ) cations in the near-surface region. When the potential is reversed, EA+ is attracted to the Stern layer to replace NO3 - , but its movement is hindered by solvophobic attractions. The outcomes will aid applications, including electrochemical devices, catalysts, and lubricants.

Electrodeposition of Ni-Co Alloys from Ionic Liquids and Their Electrocatalytic Properties

Amorphous and nanocrystalline Ni-Co alloys have been deposited on FTO glass in ethylammonium nitrate (EAN), a protic ionic liquid (PIL). In a first step, the physicochemical properties of EAN with Ni2+ and Co2+ salts have been studied as well as the electrochemical behavior of these metal cations in the PIL in order to optimize the electroplating process (Fig. 1). It was shown that when the electrodeposition of Co, Ni and Ni-Co alloys was performed on FTO glass in EAN at 60 ℃ in an oxygen-free environment, nanocrystalline Ni-Co alloys with different atomic ratios were obtained, depending on both the deposition potential and the ion concentration in solution.The electrocatalytic properties of these materials were then investigated towards the hydrogen evolution reaction (HER). It was shown that the addition of Co in Ni-based alloys can promote the HER, and most notably, amorphous Ni-Co alloys show lower overpotential or reaction rate. This work provides a new route to prepare nanocrystalline and amorphous Ni-Co alloys with different ratio in PIL for practical applications in electrocatalysis such as water splitting. Figure 1

Evolution of the La(III) ion coordination sphere in ethylammonium nitrate solution upon water addition

A thorough structural study of La(NO3)3 salt solutions in mixtures of the ethylammonium nitrate (EAN) ionic liquid (IL) and water with EAN molar fraction (χEAN) ranging from 0 to 1 has been carried out by means of X-ray absorption spectroscopy (XAS) measurements at the La K-edge and molecular dynamics (MD) simulations. Both the XAS and MD outcomes agree in finding that the composition of the La3+ ion first solvation shell undergoes steadily changes when moving from pure water to pure EAN. Upon increasing of the IL concentration, the La3+ solvation complexes progressively lose water molecules to accommodate more and more nitrate anions, and the ratio between the two ligands continuously changes across the explored composition range. The nitrate ligands coordinate the metal ion only in a monodentate fashion for the lower EAN contents, while the percentage of bidentate nitrates becomes more and more predominant as the EAN concentration increases. When moving from pure water to pure EAN, the La3+ ion coordination passes from a 9-fold tricapped trigonal prismatic geometry to a 12-fold icosahedral one, while a 10-fold coordination with bicapped square antiprism geometry is the dominant species for the mixed compositions. The remarkable flexibility of this solvation complex in accommodating a variable amount of water molecules and nitrate ligands at dependence of the system composition is key for its predominance in all the EAN/water mixtures.

Interfacial structure of protic and aprotic ionic liquid-DMSO-Li salt mixtures near charged and neutral electrodes: A Molecular Dynamics study

In this paper we report classical Molecular Dynamics simulations of the interfacial structure of two ternary mixtures, based on both a protic (ethylammonium nitrate, EAN) and an aprotic (1-ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF4) ionic liquid. A molecular solvent (dimethylsulfoxide, DMSO) and a lithium salt with common anion are the rest of the components of the mixtures. The simulations were performed with implicit graphene walls, both neutral and charged with a surface charge density of ±1 e/nm2. Density, charge and electrostatic potential profiles as well as integral capacitances were calculated for all systems. For both liquids, the evolution of the density profiles throughout the DMSO concentration range are in accordance with previously characterized bulk properties of such systems. In the case of charged interfaces, the adsorption of Li+ cations into the negative electrode was found to be possible for the protic liquid, but unfavourable in the case of the aprotic one. Moreover, the probability distribution functions for the orientation of all molecular species near the interfaces were computed, and they indicate a tendency of the solvent molecules to form a dense layer at the interface separating the ionic liquids from the electrodes. The influence of hydrogen bonds in determining the dissimilitudes between protic and aprotic mixtures is highlighted.

Micelle structure of nonionic surfactants containing carbon dioxide moieties in protic ionic liquids

Partial substitution of ethylene oxide with carbon dioxide moieties can yield greener nonionic surfactants with comparable functionalities. In water, studies showed that the incorporation of CO2 moieties suppresses the formation of liquid crystalline phases at high concentrations. A similar reduction in solvation and suppression of liquid crystal formation is observed here in the ionic liquids ethylammonium nitrate and propylammonium nitrate. Small-angle neutron scattering is used to study the solvation and packing of micelles in ionic liquids as functions of temperature, concentration, and content of CO2 moieties. By comparing with aqueous solutions, this work shows that while the nature of surfactant-solvent interaction is comparable among water and alkylammonium nitrate ILs, their behaviours in the solvated micelle shell are different. The lack of liquid crystalline phases should be attributed to the small excluded volume of micelles, which can be fine-tuned via ion design and choice of solvent.Graphical

Mixtures of ethylammonium nitrate and ethylene carbonate: Bulk and interfacial analysis

The structure and dynamics of binary mixtures of a protic ionic liquid (ethylammonium nitrate) and ethylene carbonate are studied by means of atomistic molecular dynamics simulations and experimental measurements both in bulk and at the electrochemical interface. The solubility limit was experimentally found at 0.6 carbonate molar fraction. Likewise, density and conductivity experimental data are compared with computational results. Also, distribution and correlation functions obtained from bulk simulations are analyzed in the miscible range to clarify the role of the carbonate in the coordination and diffusion of ionic species. Understanding the evolution of the hydrogen bond network is of particular importance since its strength is detected as the most relevant feature in the structural organization of the mixture. Regarding the effects of the presence of an interface, the orientations of the molecules and the density and charge profiles are calculated both in the absence and in the presence of an electric field. This analysis reveals the tendency of the carbonate to displace the ionic liquid from the near-wall region when concentration is increased.

Electrodeposition of Ni-Co alloys from neat protic ionic liquid: Application to the hydrogen evolution reaction

Amorphous and nanocrystalline Ni-Co alloys have been deposited on FTO glass in ethylammonium nitrate (EAN), a protic ionic liquid (PIL). The physicochemical properties of EAN with Ni2+ and Co2+ salts have been studied as well as the electrochemical behavior of these metal cations in the PIL in aerated atmosphere. Electrochemical studies showed that the redox reactions of Ni2+ and Co2+ leading to metal deposit on glassy carbon are not reversible in those conditions due to the formation of an oxide film. Conversely, when electrodeposition of Co, Ni and Ni-Co alloys on FTO glass in EAN was performed at 60 °C in an oxygen-free environment, nanocrystalline Ni-Co alloys with different atomic ratios were obtained depending on both the deposition potential and ion concentration in solution. The composition and the morphology of the electroplated alloys were determined by several techniques such as SEM, TEM, XRD and XPS. The electrocatalytic properties of these materials were investigated towards the hydrogen evolution reaction (HER). It was shown that the addition of Co in Ni-based alloys can promote the HER, and most notably, amorphous Ni-Co alloys shows lower overpotential or reaction rate. Up to now, the better electrocatalytic results were obtained with the amorphous Ni51.9Co48.1 alloy, electrodeposited in EAN at high potential (-1.3 V/Ag/Ag+). This work provides a new route to prepare nanocrystalline and amorphous Ni-Co alloys with different ratio in PIL for practical applications in electrocatalysis such as water splitting.

Unusual phosphatidylcholine lipid phase behavior in the ionic liquid ethylammonium nitrate

HypothesisThe forces that govern lipid self-assembly ionic liquids are similar to water, but their different balance can result in unexpected behaviour. ExperimentsThe self-assembly behaviour and phase equilibria of two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), in the most common protic ionic liquid, ethylammonium nitrate (EAN) have been investigated as function of composition and temperature by small- and wide-angle X-ray scattering (SAXS/WAXS) and small-angle neutron scattering (SANS). FindingsBoth lipids form unusual self-assembly structures and show complex and unexpected phase behaviour unlike that seen in water; DSPC undergoes a gel Lβ to crystalline Lc phase transition on warming, while POPC forms worm-like micelles L1 upon dilution. This surprising phase behaviour is attributed to the large size of the EAN ions that solvate the lipid headgroup compared to water changing amphiphile packing. Weaker H-bonding between EAN and lipid headgroups also contributes. These results provide new insight for the design of lipid based nanostructured materials in ionic liquids with atypical properties.