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Ultraviolet-induced interface reactions are used for the modification of silver nanoparticles (Ag NPs), which is controllable in both the color and the surface chemistry of the nanoparticles. The studies have shown that the color changes are directly related to the chemical components on the surface of Ag NPs and hence the correlation of the colors with the chemical states of main components on the surface of Ag NPs is made during the course of interface reactions.

Temperature dependence of the physiochemical characteristics of a room-temperature ionic liquid consisting of trimethylhexylammonium (TMHA) cation and bis(trifluoromethane) sulfonylimide (TFSI) anion containing different concentrations of LiTFSI salt was examined. Electrochemical properties of a spinel LiMn2O4 electrode in 1 M LiTFSI/TMHA-TFSI ionic electrolyte were investigated at different temperatures by using cyclic voltammetry, galvanostatic measurements, and electrochemical impedance spectroscopy. The Li/ionic electrolyte/LiMn2O4 cell exhibited satisfactory electrochemical properties with a discharge capacity of 108.2 mA h/g and 91.4% coulombic efficiency in the first cycle under room temperature. At decreased temperature, reversible capacity of the cell could not attain a satisfactory value due to the high internal resistance of the cell and the large activation energy for lithium ion transfer through the electrode/electrolyte interface. Anodic electrolyte oxidation results in the decrease of coulombic efficiency with increasing temperature. Irreversible structural conversion of the spinel LiMn2O4 in the ionic electrolyte, possibly associated with the formation of TMHA intercalated compounds and/or Jahn−Teller distortion, was considered to be responsible for the electrochemical decay with increasing cycles. [ABSTRACT FROM AUTHOR]

Vibrational spectroscopic studies have been carried out on solutions of LiBF4 in acetonitrile as a function of concentrations of lithium salt. Great changes in the vibrational characteristics of C⋮N and C−C stretches were observed as a result of solvation. The solvation numbers of Li+ determined from spectroscopic data are found to decrease from 3.2 to 1.4 with increasing concentration of the lithium salt. It is expected that the solvation number is 4 in the infinite diluted solution. Solvation structures of the lithium ion were suggested by density functional theory and the results were compared with the spectroscopic data. Changes of the ν1 mode of BF4- with concentration of the salt were also analyzed, and the bands at 763, 771, and 780 cm-1 indicate the coexisting of free ion, contact ion pairs, and dimers. The structures of ion pairs in gas phase and in acetonitrile solutions were suggested on the basis of DFT calculations. [ABSTRACT FROM AUTHOR]

The emission of NH 3 into atmosphere is seriously harmful for human health and public safety, thus the capture and recovery of NH 3 from ammonia emissions is highly desirable. In recent years, many kinds of solid adsorbents have been exploited to absorb NH 3 . However, these materials do not show the advantages of high uptake capacity and good recyclability at the same time. Here, nontoxic and low cost few-layer BiI 3 nanosheets have been prepared from bulk BiI 3 powder by a simple and efficient liquid phase exfoliation strategy using green solvents and then applied for the NH 3 capture for the first time. The results show that the adsorption capacity of NH 3 of BiI 3 nanosheets reaches up to 22.6 mmol/g at 1.0 bar and 25 °C, which approaches the record value for NH 3 adsorption. Importantly, the NH 3 uptake in BiI 3 nanosheets is completely reversible and no clear loss in uptake capacity is observed after 10 cycles of adsorption-desorption. Furthermore, the BiI 3 nanosheets exhibit remarkable selectivity for the separation of NH 3 /CO 2 at 70 °C with theoretical selectivity coefficient of 700, which is promising for the selective separation of NH 3 and CO 2 in hot tail gas of some industrial processes. Mechanism studies indicate that such superior NH 3 capacity, excellent reversibility and remarkable selectivity are primarily attributed to the Bi 3+ -NH 3 coordination interactions.

In recent years, metal-organic frameworks (MOFs) have been explored as emulsifiers for the fabrication of Pickering emulsions and then used for hybrid material synthesis and interface catalysis. Nevertheless, stimuli-responsive Pickering emulsions stabilized by MOFs have been rarely reported so far, although they are of great importance for fundamental research studies and practical applications. Herein, for the first time, triethylenetetramine (TETA)-functionalized MOFs (ZIF-90/TETA) have been designed, synthesized, and used for fabricating CO 2 -/N 2 -response Pickering emulsions. It is shown that even at the ZIF-90/TETA content of 0.25 wt %, the functional MOF can still efficiently emulsify n -hexane and water to form a high internal phase Pickering emulsion. Importantly, the Pickering emulsion can be easily and reversibly switched between emulsification and demulsification by bubbling of CO 2 and N 2 alternatively at atmospheric pressure. The possible mechanism of the CO 2 /N 2 switchable emulsion is investigated by zeta potential, water contact angle, interfacial tension, 13 C NMR spectroscopy, and an optical microscope. It is found that the acid-base reaction of CO 2 with TETA anchored on the surface of ZIF-90 leads to the production of hydrophilic ammonium bicarbonate and carbamate, which results in the emulsification of the Pickering emulsion. However, when N 2 is bubbled to remove CO 2 , the reverse reaction takes place to cause the demulsification of the Pickering emulsion. Moreover, the CO 2 /N 2 switchable Pickering emulsion has been successfully used as a microreactor for Knoevenagel reactions to demonstrate a highly efficient integration of chemical reaction, product separation, and ZIF-90/TETA recycling for a sustainable chemical process.

The nanoplasmonic metal-driven photocatalytic activity depends heavily on the spacing between metal nanoparticles (NPs) and semiconductors, and this work shows that ethylene glycol (EG) is an ideal candidate for interface spacer. Controlling the synthetic systems at pH 3, the composite of Ag NPs with EG-stabilized amorphous TiO 2 (Ag/TiO 2 -3) was synthesized by the facile light-induced reduction. It is verified that EG spacers can set up suitable geometric arrangement in the composite: the twin hydroxyls act as stabilizers to bind Ag NPs and TiO 2 together and the nonconductive alkyl chains consisting only of two CH 2 are able to separate the two building blocks completely and also provide the shortest channels for an efficient transfer of radiation energies to reach TiO 2 . Employed as photocatalysts in hydrogen evolution under visible light, amorphous TiO 2 hardly exhibits the catalytic activity due to high defect density, whereas Ag/TiO 2 -3 represents a remarkably high catalytic efficiency. The enhancement mechanism of the reaction rate is proposed by the analysis of the compositional, structural, and optical properties from a series of Ag/TiO 2 composites.

This work developed a facile colloidal route to synthesize BH 4 - -capped Pd x Ag y nanoparticles (NPs) in water using the reducing ionic liquids of [C n mim]BH 4 , and the resulting NPs were prone to form the nanocomposites with [amim] + -modified reduced graphene (RG). The removal of the metal-free inorganic ions of BH 4 - can create the profoundly exposed interfaces on the Pd x Ag y NPs during the electrooxidation, and favor the ethanol oxidation reaction (EOR) in lowering energy barrier. The counterions of [C n mim] + can gather ethanol, OH - ions, and the reaction intermediates on catalysts, and synergistically interact with RG to facilitate the charge transfer in nanocomposites. The interface-modified RG nanosheets can effectively segregate the Pd x Ag y NPs from aggregation during the EOR. Along with the small size of 4.7 nm, the high alloying degree of 60.2%, the large electrochemical active surface area of 64.1 m 2 g -1 , and the great peak current density of 1501 mA cm -2 mg -1 , Pd 1 Ag 2 @[C 2 mim]BH 4 -amimRG nanocomposite exhibits the low oxidation potentials, strong poison resistance, and stable catalytic activity for EOR in alkaline media, and hence can be employed as a promising anodic catalyst in ethanol fuel cells.

Understanding of the specific salt effect on the aggregation behavior of ionic liquids (ILs) is relevant to multiple applications. In this work, the influence of a series of 15 salts on the aggregation behavior of [C(10)mim]Br in aqueous solutions has been investigated by conductivity, fluorescence, and dynamic light scattering. It was shown that NaCl, NaBr, NaI, CH(3)CO(2)Na, NaSCN, NaNO(3), NaBrO(3), NaClO(3), C(6)H(5)COONa, Na(2)CO(3), Na(2)SO(4), Na(2)C(4)H(4)O(6), and Na(3)CH(5)O(7) have salting-out effect, whereas FeBr(3) and AlBr(3) have salting-in effect on the aggregation of [C(10)mim]Br in aqueous solutions. The effect of anions of the added sodium salts on the critical aggregation concentration (CAC), degree of anionic binding (beta), and aggregation number (N(agg)) of the IL basically follows the Hofmeister series, and the CAC values decrease but the beta and N(agg) values increase with increasing concentration of the salts. Hydrophobicity of the anions is suggested to play important roles in the salt effect on the aggregation of [C(10)mim]Br in aqueous solutions. Furthermore, the IL aggregates were found to grow slowly as the increase of the salt concentrations under studied static conditions, and resulting in the increased aggregation number of the IL. These results are expected to be useful in the applications of ionic liquids.

Densities, conductivities, and polarity indexes of pyrene for aqueous solutions of a series of ionic liquids [C(n)mim]Br (n = 4, 6, 8, 10, 12) and [C4mim][BF4] have been determined at 298.15 K as a function of ionic liquid concentrations. It was shown that possible aggregation appeared for the ionic liquids in aqueous solutions except for [C4mim]Br. The critical aggregation concentration (CAC) of the ionic liquids, the ionization degree of aggregates (beta), the standard Gibbs energy of aggregation (Delta G(m)(o)), the limiting molar conductivity (Lambda(m)(o)), and the standard partial molar volume (V(m)(o)) for the ionic liquids were derived from the experimental data. The dependence of the CAC, Delta G(m)(o), Lambda(m)(o), and V(m)(o) on the length of the alkyl chain of the cations was examined. It was further suggested from volumetric data that a micelle was formed for [C8mim]Br, [C10mim]Br, and [C12mim]Br in aqueous solutions. Their apparent molar volumes at the critical micelle concentration (V Phi,CMC), apparent molar volumes in the micelle phase (V(Phi)(mic)), and the change of their apparent molar volume upon micellization (Delta V Phi,m) were calculated by application of the pseudophase model of micellization. In addition, the average aggregation number of [C(n)mim]Br (n = 8, 10, 12) has been determined by the steady-state fluorescence quenching technique, and predicted from a simple geometrical mode. It is found that the experimental values are in good agreement with the predicted ones.

Temperature dependence of the physiochemical characteristics of a room-temperature ionic liquid consisting of trimethylhexylammonium (TMHA) cation and bis(trifluoromethane) sulfonylimide (TFSI) anion containing different concentrations of LiTFSI salt was examined. Electrochemical properties of a spinel LiMn(2)O(4) electrode in 1 M LiTFSI/TMHA-TFSI ionic electrolyte were investigated at different temperatures by using cyclic voltammetry, galvanostatic measurements, and electrochemical impedance spectroscopy. The Li/ionic electrolyte/LiMn(2)O(4) cell exhibited satisfactory electrochemical properties with a discharge capacity of 108.2 mA h/g and 91.4% coulombic efficiency in the first cycle under room temperature. At decreased temperature, reversible capacity of the cell could not attain a satisfactory value due to the high internal resistance of the cell and the large activation energy for lithium ion transfer through the electrode/electrolyte interface. Anodic electrolyte oxidation results in the decrease of coulombic efficiency with increasing temperature. Irreversible structural conversion of the spinel LiMn(2)O(4) in the ionic electrolyte, possibly associated with the formation of TMHA intercalated compounds and/or Jahn-Teller distortion, was considered to be responsible for the electrochemical decay with increasing cycles.

The effect of nanosized Al2O3/ZnO fillers on the interactions in PEO-NaSCN polymer electrolytes has been studied by FT-IR, XRD, and DTA measurements. The experimental results are discussed according to the grain boundary effect, the principle of Lewis acid-base, and epitaxial effect. It is shown that the hard Lewis acid centers on the surface of Al2O3 exhibit strong interactions with ether oxygens in PEO, even with ether oxygens that coordinated to Na+. Therefore, the modes of the interaction of Al2O3 with PEO-NaSCN electrolytes are dependent on the salt content. Al2O3 cannot influence the ionic association in P(EO)8NaSCN electrolyte, but do reduce significantly the solvating ability of PEO toward NaSCN in P(EO)60NaSCN electrolyte. However, NaSCN in P(EO)20NaSCN-30%Al2O3 nanocomposite appears as a state that resembles the situation of NaSCN in PEO amorphous phase. In contrast with Al2O3, the epitaxial effect of ZnO is not found in the interested systems where only weaker interaction is observed between ZnO and ether oxygen, and the modes of interaction of ZnO with PEO-NaSCN electrolytes are hardly related to the salt content. In addition, the soft Lewis acid groups on ZnO surface exhibit stronger complexation with SCN- in PEO-NaSCN electrolytes, and both can form the complex anion ZnO...SCN-.