As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.

Developing effective catalysts based on earth abundant elements is critical for CO 2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (j CO) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N 3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a j CO of 14.0 mA cm −2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher j CO of 29.7 mA cm −2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N 3 site, which facilitates the formation of the key intermediate COOH * through a lowered free energy barrier.

The pyridinium-based ionic liquids (ILs) N-butylpyridinium tetrafluoroborate ([BPy][BF 4 ]), N-hexylpyridinium tetrafluoroborate ([HPy][BF 4 ]), and N-octylpyridinium tetrafluoroborate ([OPy][BF 4 ]) were found to be effective for the selective removal of aromatic heterocyclic sulfur compounds from diesel at room temperature. The results suggested that the structure and size of the cation greatly affect the extractive performance of ILs. The extractive performance using pyridinium-based ILs followed the orderand for the IL, the sulfur removal selectivity of sulfur compounds followed the order thiophene (TS) < benzothiophene (BT) < dibenzothiophene (DBT) under the same conditions. The pyridinium-based ILs would not contaminate the diesel due to their insolubility. On the other hand, diesel has a certain solubility in pyridinium-based ILs, varying from 0.49 wt % for [BPy][BF 4 ] to 1.97 wt % for [OPy][BF 4 ]. According to the results, [HPy][BF 4 ] and [OPy][BF 4 ] might be used as promising solvents for the extractive desulfurization of diesel.

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The capacity of NH3 in PIL [Bim][NTf2] was up to 2.69 mol NH3 per mol IL under ambient conditions.

The Brønsted acidic ionic liquids 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO 4 ]) and N-butylpyridinium hydrogen sulfate ([C 4 Py][HSO 4 ]) were used as extractant and catalyst for desulfurization of diesel. The results show that [BMIM][HSO 4 ] is better as extractant and catalyst than [C 4 Py][HSO 4 ] during the desulfurization process. The sulfur removal of dibenzothiophene (DBT) in n-octane was 99.6% in 90 min under the conditions of V model oil /V IL = 2 : 1 and H 2 O 2 /DBT molar ratio at 5 (O/S = 5), at room temperature. The sulfur removal of four sulfur compounds by extraction and catalytic oxidation process followed the order of DBT > benzothiophene (BT) > thiophene (TS) > 4,6-dimethyldibenzothiophene (4,6-DMDBT). Moreover, the [BMIM][HSO 4 ] can be recycled for at least 6 times with a little decrease in the desulfurization activity. The sulfur removal of diesel fuel containing sulfur content of 97 ppm is 85.5%, which was much better than desulfurization performance by simple extraction with IL (11.0%). In this extraction and oxidative desulfurization process, DBT was oxidized to corresponding sulfone by H 2 O 2 with Brønsted acidic IL [BMIM][HSO 4 ] which served as not only extractant but also catalyst.

The efficient ammonia absorption capacities of hydroxyl-functionalized ILs are due to the strong hydrogen bonding between the N atom of NH3 and the H atom of the hydroxyl on cation.

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