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Na-ion batteries are becoming increasingly attractive as a low cost energy storage device. Sodium vanadium fluorophosphates have been studied extensively recently due to their high storage capacity and high discharge voltage. Shape and size often have a crucial influence over the properties. The controlling synthesis of nanoparticles with special microstructures is significant, which becomes a challenging issue and has drawn considerable attention. In this study, Na3(VPO4)2F3 nanoflowers have been synthesized via a pH-regulative low-temperature (120 °C) hydro-thermal route. In particular, it is a green route without any organic compounds involved. The hydro-thermal reaction time for the formation of Na3(VPO4)2F3 nanoflowers has also been investigated. A weak acid environment (pH = 2.60) with the possible presence of hydrogen fluoride molecules is necessary for the formation of the desired nanoflower microstructures. Compared to the nanoparticles obtained by Na2HPO4·12H2O, the as-synthesized Na3(VPO4)2F3 nanoflowers showed an excellent Na-storage performance in terms of superior cycle stability, even without any further carbon coating or high-temperature treatment. [ABSTRACT FROM AUTHOR]

In this work, a novel IL-based synergistic extraction system utilizing the ionic liquid tricaprylmethylammonium nitrate ([A336][NO3]) and the commercial extractant di(2-ethylhexyl) 2-ethylhexyl phosphonate (DEHEHP) was developed for the extraction of rare earth (RE) nitrates. Pr(iii) was used as a model RE and the effects of key factors, i.e. the ratio of [A336][NO3] to DEHEHP, the acidity of feed solutions, and the concentration of a salting-out reagent, were systematically studied. Our results demonstrate that the mixture of [A336][NO3] and DEHEHP had an obviously synergistic extraction effect for the extraction of Pr(iii). The maximum synergistic enhancement coefficient of 3.44 was attained at XA = 0.4 (v%). Alternatively, a mixture of [A336][Cl] and DEHEHP hardly extracted Pr(iii) from chloride media. Moreover, we investigated the Pr(iii) extraction mechanism and demonstrated that Pr(iii) can be extracted as the neutral complexation species Pr(NO3)3·xDEHEHP and the ion-type species [A336]y·Pr(NO3)3+y. These extraction processes can effectively hamper the release of organic cation-ligands into the aqueous phase. The synergistic extraction effect is mainly derived from the enhanced solubility of the extracted species in the ionic liquid phase. The extraction behaviors of Pr(iii) could be properly described by Langmuir and pseudo-second-order rate equations. An increase in temperature was unfavorable for the extraction reaction but greatly improved the extraction rate. Interestingly, the mixed IL extraction system has an obviously synergistic extraction effect for light REs (LREs, La–Eu), but an anti-synergistic effect for heavy REs (HREs, Gd–Lu, Y), thus indicating that our synergistic extraction system is helpful for the separation of LREs from HREs. In addition, the high selectivity between REs and non-REs suggested that the recovery of REs from a complicated high-salt leachate could be highly possible. It demonstrates that the IL-based synergistic extraction strategy developed in this work is promising and sustainable, and as a result the development of an IL-based synergistic extraction process for the recovery of REs is straightforwardly envisaged. [ABSTRACT FROM AUTHOR]

We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1−xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80–140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g−1 and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds. [ABSTRACT FROM AUTHOR]

Hydrothermal carbon spherules (HCSs) can be loaded with a variety of metal nanoparticles for various applications. In this work, three types of HCSs were prepared from saccharides (mono-, di- and poly-saccharides) by a modified hydrothermal method using glucose, sucrose and starch as sources. Au nanoparticles can be deposited onto the HCSs through a regular adsorption process. For comparison, the HCSs made from mono-saccharide glucose (HCSs-M) have a higher adsorption capacity for Au(iii) from aqueous acidic chloride media. The adsorption behaviors for AuCl4− by HCSs-M were systematically investigated. HCSs-M shows a high selectivity for Au(iii) towards Pd(ii), Pt(vi), Rh(iii) and some relevant base metals such as Fe(iii), Co(ii), Cu(ii) and Ni(ii). An extra reductant glycine can not only significantly improve the adsorption capacities and selectivity, but also accelerate the adsorption rate. The Langmuir isotherm model and the 2nd-order kinetics model can properly describe the adsorption behaviors of AuCl4−. The adsorption mechanism of Au(iii) by HCSs has been confirmed by XPS, XRD, TG, FTIR, SEM and TEM techniques, which demonstrate that AuCl4− deposited onto the HCSs has been reduced to Au0. On the basis of this phenomenon, a reduction–deposition coupled mechanism has been proposed. The current research illustrates the prospect for HCSs to be used as effective adsorbents for the selective adsorption separation of Au(iii) from chloride media. It also demonstrates the possibility to integrate the selective recovery of gold from complex industrial waste streams and the fabrication of functional carbon materials through loading with gold nanoparticles. [ABSTRACT FROM AUTHOR]

The Brønsted acidic ionic liquids 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]) and N-butylpyridinium hydrogen sulfate ([C4Py][HSO4]) were used as extractant and catalyst for desulfurization of diesel. The results show that [BMIM][HSO4] is better as extractant and catalyst than [C4Py][HSO4] during the desulfurization process. The sulfur removal of dibenzothiophene (DBT) in n-octane was 99.6% in 90 min under the conditions of Vmodel oil/VIL= 2 : 1 and H2O2/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][HSO4] 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 H2O2with Brønsted acidic IL [BMIM][HSO4] which served as not only extractant but also catalyst. [ABSTRACT FROM AUTHOR]

We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1-xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80-140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g(-1) and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds.