Ammonia (NH3) is a globally important commodity for fertilizer production, but its synthesis by the Haber-Bosch process causes substantial emissions of carbon dioxide. Alternative, zero-carbon emission NH3 synthesis methods being explored include the promising electrochemical lithium-mediated nitrogen reduction reaction, which has nonetheless required sacrificial sources of protons. In this study, a phosphonium salt is introduced as a proton shuttle to help resolve this limitation. The salt also provides additional ionic conductivity, enabling high NH3 production rates of 53 ± 1 nanomoles per second per square centimeter at 69 ± 1% faradaic efficiency in 20-hour experiments under 0.5-bar hydrogen and 19.5-bar nitrogen. Continuous operation for more than 3 days is demonstrated.

No abstract

The speciation of a family of inexpensive, easily prepared protonic ionic liquids, their physico-chemical properties and their performance as catalysts in the model esterification reaction have been correlated.

The synthesis and characterisation of new hydrogen-bond-rich ionic liquids and studies of their catalytic performance in Diels–Alder reactions are described. An increase in the number of hydroxyl groups present in the ionic liquid structure resulted in higher efficiency.

An overview of the field of ionic liquids is presented, including the nomenclature and types of ionic liquids. Their synthesis and purification methods are described, along with typical characterisation procedures and general physico‐chemical properties. The various applications of ionic liquids are also summarised including in batteries, in green chemistry as low vapour pressure solvents, in medicinal chemistry and in protein stabilisation.

The kinetics of polymerization of Bisphenol-A diglycidyl ether (DGEBA), a well-known epoxy resin, with two ionic amines 1-(3-aminopropyl)-3-butyl­imidazolium bis­(trifluoro­methyl­sulfonyl)­imide ([apbim]­[NTf2]) and the tetrabutyl­ammonium leucine ([N4444]­[Leu]) have been studied with the use of differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) at various temperatures. We found many fundamental differences between the progress of this reaction with respect to the classical system (curing of epoxy resin with ordinary nonconducting hardeners). One of the most significant differences is related to the mechanism of polymerization. It is worthwhile to mention that usually the autocatalytic model is used to describe the curing of DGEBA with ordinary amines. However, herein, the kinetic curves followed a clearly exponential shape characteristic of first-order kinetics. We claim that the change in mechanism of polymerization is related to the presence of a conducting amine that acts as both the substrate and the catalyst of this specific chemical conversion. Also, it is presented that the pace of the reaction only weakly depends on temperature, which is reflected in the relatively low activation energy. On the other hand, the degree of monomer conversion stays around 45%–70% as typically reported for the polymerization of DGEBA with nonconducting hardeners. In addition, we measured the time evolution of dc conductivity as the reaction proceeded and observed that a change in this parameter correlates very well with the monomer conversion in contrast to the reaction of nonconducting systems. Finally, ionic conductivity of the resulted cured samples was investigated and found to be quite significant at the glass transition temperature with respect to other polymerized ionic liquids.

Thermal energy storage technology utilizing phase‐change materials (PCMs) can be a promising solution for the intermittency of renewable energy sources. This work describes a novel family of PCMs based on the pyrazolium cation, that operate in the 100–200 °C temperature range, offering safe, inexpensive capacity and low supercooling. Thermal stability and extensive cycling tests of the most promising PCM candidate, pyrazolium mesylate (Tm=168±1 °C, ΔHf=160 J g−1±5 %, ΔHtotalv=495 MJ m−3±5 %) show potential for its use in thermal storage applications. Additionally, this work discusses the molecular origins of the high thermal energy storage capacity of these ionic materials based on their crystal structures, revealing the importance of hydrogen bonds in PCM performance.

Phase change materials (PCMs) which melt in the temperature range of 100-230 °C, are a promising alternative for the storage of thermal energy. In this range, large amounts of energy available from solar-thermal, or other forms of renewable heat, can be stored and applied to domestic or industrial processes, or to an Organic Rankine Cycle (ORC) engine to generate electricity. The amount of energy absorbed is related to the latent heat of fusion (ΔH f) and is often connected to the extent of hydrogen bonding in the PCM. Herein, we report fundamental studies, including crystal structure and Hirshfeld surface analysis, of a family of guanidinium organic salts that exhibit high values of ΔH f , demonstrating that the presence and strength of H-bonds between ions plays a key role in this property. File list (3) download file view on ChemRxiv Manuscript.pdf (865.17 KiB) download file view on ChemRxiv Supplementary information.pdf (3.39 MiB)