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Graphite can be successfully used as an anode for potassium-ion batteries (PIBs), while its conversion to KC

Trichloroacetonitrile has been found to be an efficient dehydrating agent for a range of aldoximes including aromatic and heterocyclic aldoxime yielding the corresponding nitriles in moderate to go...

Solid-state Li batteries are receiving increasing attention as a prospective energy storage system due to the high energy density and improved safety. However, the high interfacial resistance between solid-state electrolyte and electrode results in sluggish Li

Platinum is generally known as the most effective electrocatalyst for hydrogen evolution reaction because it can greatly lower the overpotential and accelerate the reaction kinetics, while its commercial potential always suffers from scarcity, high cost, low utilization, and poor durability particularly in acidic electrolytes. We herein demonstrate a facile method to improve the hydrogen evolution performance of Pt-based electrocatalysts by simply decorating the-state-of-the-art and commercially available Pt/C with hydrophobic protic ([DBU][NTf2]) or aprotic ([BMIm][NTf2]) ionic liquid. The current densities of [BMIm]@Pt/C and [DBU-H]@Pt/C with 10% ionic liquid at an overpotential of 40 mV are 2.81 and 4.15 times, respectively, higher than that of the pristine Pt/C. More importantly, ionic liquid-decoration significantly improves the long-term stability of Pt nanoparticles. After 8 h of chronoamperometric measurements, [DBU-H]@Pt/C and [BMIm]@Pt/C can still retain 83.7% and 78.3% of their original activity, respectively, which is much higher than that of the pristine Pt/C (24.4%). The improved performance of Pt/C decorated with ionic liquid is considered to arise from the improved proton conductivity (particularly for protic ionic liquid) and hydrophobic microenvironment created by the supported ionic liquid phase. The presence of ionic liquid layer not only de-coordinates H+ from hydronium ions nearby the Pt nanoparticles, but it also protects Pt nanoparticles from dissolution in the acidic media.

As the most abundant renewable aromatic resource on Earth, lignin is a preferred starting material for producing bulk chemicals via a sustainable route. In this study, we provide a novel and efficient "clip-off" approach for producing methyl

Capacity retention is one of the key factors affecting the performance of silicon (Si)-based lithium-ion batteries and other energy storage devices. Herein, a three dimension (3D) network self-healing binder (denoted as PVA + LB) consisting of polyvinyl alcohol (PVA) and lithium metaborate (LiBO

Graphene has long been considered a superlative protection material due to its extraordinary characteristics and properties. However, its high electrical conductivity can facilitate the electrochemical corrosion of metal, which strongly limits its anti-corrosion applications. Here, we developed a facile fluorination strategy to suppress the corrosion promotion activity of graphene. Fluorinated reduced graphene oxide (FrGO) exhibited low electrical conductivity (3.643 × 10−13 S/cm), which proved unable to trigger micro-galvanic corrosion. Furthermore, acridizinium ionic liquid (IL) [MAc]Br was noncovalently grafted on FrGO to achieve the well dispersion in the polymer matrix. Results revealed that FrGO-IL nanohybrid can be stably dispersed in the epoxy resin. Electrochemical impedance spectroscopy revealed that incorporating a small percentage of FrGO-IL into waterborne epoxy matrix effectively improved the corrosion resistance performance of the coating by exerting the superior shielding effect and inhibiting the ability for micro-galvanic corrosion. Moreover, local electrochemical and scratching tests further confirmed that FrGO-IL significantly reinforced the corrosion protection capability of waterborne epoxy coating because the well-dispersed nanohybrid enhanced the integrity of the composite coating, effectively utilizing the labyrinth effect. Our finding could inspire the development of new graphene-based materials with superior protection properties for metal materials.

Designing highly stable and reusable catalytic systems based on Au nanoparticles (NPs) is a significant challenge in nanocatalysis research. Here, we have fabricated polyvinyl alcohol (PVA) nanofibrous mat/Au NP composite catalysts with NPs in uniform size and good distribution by use of a developed in situ growth approach. In this method, Au seeds were first adsorbed on PVA nanofibrous mat surfaces rather than on relatively large Au NPs and then used to grow NPs in Au seed solution; thus, the steric hindrance effect was alleviated and a high loading was used for Au NPs up to 11 wt %. Strong interfacial interactions between the Au NPs and the PVA nanofibrous mats due to introducing a large number of hydrogen bonds provide high thermal stability for the PVA side chains, long-term catalytic stability, and excellent reusability. Consequently, the proposed in situ grown PVA/Au NP nanofibrous mats produce high catalytic activity for at least 15 cycles over a 30 d period. This work provides a potential approach for fabricating highly stable and reusable metal NPs on polymer nanofibrous mats to facilitate a wide variety of applications.

In this study, a new DMF-derived ionic liquid electrolyte [EDMF]BF4 was prepared, characterized and applied as a high-capacitance electrolyte for electric double-layer capacitors (EDLCs). [EDMF]BF4 was measured to have very high ionic conductivity and low viscosity (24.8 mS cm−1 and 21.6 mPa s at 25 °C), as well as a comparable electrochemical window (4.4 V, on a GC electrode) with [EMIm]BF4, which is one of the most widely studied ionic liquid electrolytes with high performance. Therefore, [EDMF]BF4 was used as a non-volatile electrolyte for activated carbon-based EDLCs. The [EDMF]BF4-based EDLCs are capable to operate stably over a voltage of 2.7 V, and the specific capacitance of activated carbon was determined to be 165 F g−1 (100th cycle at 1 mA cm−2 and 30 °C), which is much larger than in the case of [EMIm]BF4 (126 F g−1). Besides, [EDMF]BF4 showed lower ohmic resistance and double layer resistance than [EMIm]BF4 in EDLCs. The high performance of [EDMF]BF4 electrolyte should be related to the quasi-linear [EDMF] cation of moderate size, which is presumably more suitable for enhanced ion mobility and compact electric double layer.

In this study, the anion exchange reaction of an organic cation chloride with excess KHCO2 to synthesize formate-based ionic liquids (ILs) was performed in water, and the water-miscible IL products were easily obtained via salting-out phase separation caused by the excess KHCO2. According to the synthesis results, a set of heuristic rules could be generated as follows. First of all, the more “hydrophobic” ILs required less amount of excess KHCO2 for salting-out phase separation. Secondly, the amphiphilic ILs with a long cationic alkyl chain (e.g., octyl) are likely to form reverse micelles to encapsulate inorganic salt (i.e., KCl), resulting in relatively high residual contents of K+ and Cl−. Lastly, cooling would exert a positive effect on the salting-out phase separation and thus expand the application range of this method. For example, [C2-MIm]HCO2 was prepared at −18 °C, because it has to be phase-separated out by cooling. The basic properties of these ILs were also thoroughly characterized and analyzed, such as melting point, thermal decomposition temperature, density, refractive index, surface tension, viscosity and conductivity etc.

A simple method for the preparation of nitriles in moderate to good yield has been achieved by treatment of aromatic and heterocyclic aldoximes with malononitrile in water at reflux in the presence of copper acetate as catalyst. Arylaldoximes with an electron-donating group showed the highest reactivity, their conversion being achievable at room temperature.

A mild one-pot method for the direct conversion of aryl, heteroaryl and alkyl aldehydes into nitriles was achieved by forming the corresponding oximes in situ with NH2OH and allowing them to react with CuO and acetonitrile. Yields of the 13 nitriles prepared were moderate to very good (62–91%).

Alkoxy chain effect on the viscosity of ionic liquids has been extensively studied by experiments in order to disclose the relationship between viscosity and structure. A free-volume model was used to interpret the mechanism of the alkoxy chain effect, suggesting that flexible alkoxy chains can improve the viscosity of ionic liquids owing to the increase of free volume. Computational studies revealed that the improvement of viscosity arises from the less effective packing between flexible alkoxy chains as well as the reduction in electrostatic interaction between cations and anions. However, few computational studies have been undertaken to address the relation among free volume, electrostatic interaction, and side chain flexibility of ether-functionalized ionic liquids. In this work, we develop a general amber force field (GAFF) for ether-functionalized ionic liquids by following the traditional procedure of parameterizing GAFF for ionic liquids. Our work demonstrates that the alkoxy chain effect on the viscosity of ionic liquids can be qualitatively captured by GAFF without any optimizations. Analysis of electrostatic interactions between cations and anions in molecular dynamics (MD) simulations advances our understanding of the alkoxy chain effect from various aspects. Finally, we propose for the first time that the total free volume can further be divided into two portions, which are associated with electrostatic interactions between cations and anions.

In this paper, the influence of film thickness on the layer instability mode of a thin polymer bilayer (poly(methylmethacrylate) (PMMA)/polystyrene (PS)/Si substrate) has been investigated. The experimental results show that kinetic forces can greatly influence the instability process of the thin polymer bilayer. In the case of PS-2.4K (Mw-PS = 2.4 kg mol−1), only the PS layer ruptures between the PMMA layer and the solid substrate and the dewetting is kinetically controlled. In the case of PS-31K (Mw-PS = 31 kg mol−1), the instability of the polymer bilayer changes from a kinetically controlled one to a thermodynamically controlled one with the increase of PS film thickness. In the case of PS-97K (Mw-PS = 97 kg mol−1), only the PMMA layer ruptures on the PS layer and the dewetting process is a thermodynamically controlled one. Besides, the influence of the instability mode on the template-assisted dewetting process of the thin polymer bilayer also was studied. After annealing the pre-patterned bilayer, in the case of the kinetically controlled dewetting, the PMMA film bends to conform to the buried PS–PMMA interface and concave half cylinder grooves form during the dewetting process; however, in the case of the thermodynamically controlled dewetting, PMMA chains move to the top of cylinder stripes and obvious trenches are found after PMMA chains are etched. This proposes a simple method to obtain different surface structures by changing the instability mode of the thin polymer bilayer.

In this study, the amount of free volume in ionic liquids (ILs) was calculated and found to be almost half to that of their isoelectronic neutral analogues. MD simulations revealed that the significantly compressed free volume in the ILs was dominantly attributed to the strong inter-ion electrostatic interactions, which are comparable to the application of an external pressure of ∼250 MPa to the neutral analogues. Furthermore, the change in the free volume shows an interconnection with other properties of ILs, especially viscosity. The inherent high viscosity of ILs was quantitatively correlated to a low free volume available for mass transfer, and the sharp decrease in the viscosity of ILs with the addition of organic solvents was essentially caused by the introduction of free volume.

The preparation of ionic liquids most often involves the use of organic solvents or hazardous chemicals, especially for hydrophilic ionic liquids prepared from metathesis reaction. In this study, the salting-out effect was proposed to promote the metathesis reaction to afford water-miscible ionic liquids. The reaction proceeds in aqueous solution saturated with an inorganic precursor salt. After reaction for only 10 min, the hydrophilic product can be easily obtained by spontaneous liquid–liquid phase-separation caused by the salting-out effect, followed by concentration and filtration. In this process, no organic solvents or hazardous chemicals are required, and the saturated solution and inorganic by-product can be easily reused and recycled respectively.

An efficient and eco-friendly process is proposed for sugarcane bagasse liquefaction under mild condition using IL catalyst and environmental friendly solvent of ethanol/H2O. The relationship between IL acidic strength and its catalytic performance is investigated. The effects of reaction condition parameters such as catalyst dosage, temperature, time and solvent are also intensively studied. The results show that ethanol/H2O has a significant promotion effect on the simultaneous liquefaction of sugarcane bagasse carbohydrate and lignin. 97.5% of the bagasse can be liquefied with 66.46% of volatile product yield at 200°C for 30min. Furthermore, the IL catalyst shows good recyclability where no significant loss of the catalytic activity is exhibited even after five runs.

Instead of being seen as alternative solvents and electrolytes for organic reactions, catalysis, separation, electrochemistry, and so on, ionic liquids (ILs) consisting of discrete cations and anions have recently emerged as versatile building blocks for advanced functional materials. A number of functional ILs and IL-containing composite materials have been realized by either chemical modification (covalent functionalization or ion-exchange metathesis) or physical integration of ILs and traditional materials. The unique structure and behavior of ILs as a platform not only provides additional opportunities to adjust the physicochemical properties of these ionic materials for task-specific applications, but also offers other attractive features such as intrinsic ionic conductivity and high thermal, chemical, and electrochemical stability. These soft materials combine the favorable features of ILs and the original chemistries of the functional groups or materials; some even possess unexpected functions resulting from synergetic interaction between these two components. Materialization of ILs is truly a novel, promising research direction for both IL chemistry and materials science. In this article, we review recent advances in IL-based functional materials, focusing on smart and sensitive materials, optical materials, energetic materials, and IL/carbon hybrid materials.

Highly efficient and cost-effective electrocatalysts towards both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are critical for the large-scale and environmental-friendly hydrogen production. Here we report the facile synthesis of a novel bifunctional catalyst, mesoporous Co3O4 with surface decorated epitaxial S-doped CoO layers (S-CoO/Co3O4), via a simple solution-combustion and thioacetamide-sulfidation method. S-CoO/Co3O4 shows excellent electrochemical catalytic activity and stability in 1 M KOH with small overpotentials of 275 mV for OER and 181 mV for HER at 10 mA cm−2 on a rotating disk electrode. Moreover, when loaded on nickel foam and used as both cathode and anode for overall water splitting, the current density reaches 10 mA cm−2 at a relatively low voltage of 1.60 V and degrades for only ~ 5.7% after 20 h operation. The excellent electrochemical performance is mainly attributed to the highly active surface S-doped CoO species, which also acts as the protective buffer layer for the inner bulk phase and results in enhanced stability. Density functional theory calculations show that the S-doping in CoO and Co3O4 can accelerate the carrier transport, promoting the overall electronic conductivity and electrochemical catalytic activity.

In this study, an efficient strategy is proposed for selective methyl levulinate production from duckweed, a typical fast-growing aquatic microalgae in warm and humid regions, in the presence of acidic ionic liquids (ILs). The results show that IL structure has a significant effect on its acidic strength, which finally determines the process efficiency for levulinate methyl generation. With the optimized catalyst of [C3H6SO3HPy]HSO4, 88.0% duckweed is consumed, resulting in a comparable methyl levulinate yield of 73.7% and a process efficiency of 81.8% at 170 °C for 5 h. Furthermore, this process is substantially influenced by the reaction condition, particularly, it is significantly temperature-dependent. In addition, solvent has a remarkable intensified effect on the process efficiency, which dramatically decreases from 81.8 to 53.7% when methanol is replaced by water.

A numerical method is developed to compute the development of molecular weight distribution (MWD) curves of linear polymers undergoing chain scission. The method can be applied to complex chain scission kinetics and for arbitrarily complex initial MWD curves. Our method is based on the method of lines (MoL). Different from the existing numerical scheme, we propose the use of logarithmically spaced points. This development ensures the accuracy of the computed MWD curves at low molecular weights, and it does not require a very fine discretization to produce an accurate result.

The Hildebrand solubility parameters of 10 ionic liquids were investigated using the approach of intrinsic viscosity. Effects of dimethylacetamide (DMA) fraction in ionic liquids and dissolution temperature on the Hildebrand solubility parameter were also studied. Moreover, cohesive energy density, molar internal energy and enthalpy of dissolution were calculated. Cation and anion of an ionic liquid shows a significant influence on the solubility parameter. The values of ionic liquids containing BMIM cations are in the following order: [PF 6 ] > [Tf 2 N] > [Cl], while those of ionic liquids containing EMIM cations are in the order: [BF 4 ] > [DEPO 4 ] > [AC]. Ionic liquid containing HOEMIM exerts the highest solubility parameter than that containing MBPYRRO or BMIM. Considering effect of varying DMA fraction, the Hildebrand solubility parameters of the mixtures do not correspond to the mixing rule. Their values tend to be closer to those of the ionic liquids than that of DMA for 40–90 vol% DMA added in the ionic liquids (1-Ethyl-3-methylimidazolium acetate (EMIM-AC) and 1-Butyl-3-methylimidazolium chloride (BMIM-Cl)). With increasing temperature from 25 to 60 °C, decreases of Hildebrand solubility parameters from 25.2 to 24.7 for EMIM-AC and the mixture of EMIM-AC/DMA (60–40 v/v) were obtained. The cohesive energy densities of ionic liquids at the different conditions are proportional directly with the Hildebrand solubility parameter. The molar internal energy and the enthalpy of dissolution decrease with increasing DMA fraction in ionic liquids, while they are almost constant or show slight decreases with the increase of dissolution temperature for EMIM-AC and the mixture of EMIM-AC/DMA (60–40 v/v), respectively.

Commercial poly(L-lactide) is typically heterogeneous in chain structure due to the existence of a small amount of D-lactyl units that are produced by the racemization reactions during the synthesis. In this article, the stereochemical heterogeneity of two commercial poly(L-lactide) was investigated with temperature rising elution fractionation (TREF) and successive self-nucleation/annealing (SSA) thermal fractionation. For both samples, three fractions were collected and characterized with rotatory power analysis and DSC. The fractions show distinct optical purity and DSC results, which reflect the structure differences among them directly. After SSA treatment, the observation of multiple endotherms for each physically separated fraction confirms the fractionated sample contains a heterogeneous intermolecular and intramolecular distribution of defects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

To elucidate the effect of fiber structure on the properties of the electrospun gelatin/PCL hybrid membranes, three types of fibers with different structures, i.e., core-shell, blend, and mixed fibers were fabricated. The crystallinity, wettability, swelling degree, and mechanical properties of the hybrid membranes were compared. It was found that the crystalline characteristics of PCL in the core-shell fibers were different from the fibers fabricated by the other two methods. That is, the orientation degree of the PCL chains in the core-shell fibers was higher than that in both blend and mixed fibers. The wettability of the hybrid membrane was dependent on both the composition and structure of the electrospun fibers. Blended fibers exhibited the highest hydrophobicity because of the enrichment of PCL at the fiber surface. Contrarily, the mixed fibers possessed the highest mechanical strength of 3–5.18 MPa. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A new series of low-melting ammonium salts based on the [nido-7,8-C2B9H12]– anion have been synthesized and characterized, and their physicochemical properties including spectroscopic properties, thermal properties, surface properties, solubility, density, viscosity, electrochemical properties, and tribological properties have been studied in detail. In comparison with previously reported carborane-derivatized imidazolium or pyridinium salts, these diether-functionalized ammonium salts display lower phase transition temperatures (Tg = –76 to –57 °C), and four exist as liquids at room temperature due to their flexible alkoxy chains. TGA analysis revealed that the weight loss rates of these carborane-derivatized low-melting salts were ca. 30–80 wt.-% after thermal decomposition, which is different from the traditional RTILs. SEM images showed that the resulting residue had hollow reticular shell morphology, and XPS and XRD analyses indicate that the main components of the skeleton are B2O3 and amorphous carbon. This provides a new strategy for preparing new inorganic porous materials by thermal decomposition of these low-melting salts.

A facile strategy was proposed for synthesizing chitosan-O-poly(e-caprolactone) (CS-O-PCL). Stoichiometric sodium dodecyl sulfate–chitosan complex (SCC) which was soluble in common organic solvents was adopted as an intermediate. Regioselective conjugation of PCL onto SCC could be achieved through condensation reaction between isocyanate-terminated PCL and hydroxyl groups of chitosan. The grafting level of PCL could be modulated by varying PCL/SCC weight ratio. SDS was removed from SCC-O-PCL using trihydroxymethylamine (Tris) as a decomplexation agent. The self-assemble behavior of the amphiphilic copolymers was studied by fluorometry, TEM and laser light scattering. The morphology of the CS-O-PCL nanoparticles was found to be dependent on PCL grafting level. Both spherical micelles and vesicle could be formed by dialysis method.

A new series of ionic liquids composed of three cyclic sulfonium cations and four anions has been synthesized and characterized. Their physicochemical properties, including their spectroscopic characteristics, ion cluster behavior, surface properties, phase transitions, thermal stability, density, viscosity, refractive index, tribological properties, ion conductivity, and electrochemical window have been comprehensively studied. Eight of these salts are liquids at room temperature, at which some salts based on [NO(3)](-) and [NTf(2)](-) ions exhibit organic plastic crystal behaviors, and all the saccharin-based salts display relatively high refractive indices (1.442-1.594). In addition, some ionic liquids with the [NTf(2)](-) ion exhibit peculiar spectroscopic characteristics in FTIR and UV/Vis regions, whilst those salts based on the [DCA](-) ion show lower viscosities (34.2-62.6 mPa s at 20 degrees C) and much higher conductivities (7.6-17.6 mS cm(-1) at 20 degrees C) than most traditional 1,3-dialkylimidazolium salts.

A novel type of linear copolymer composed of poly(ethylene glycol) (PEG) with 5,5′-azodisalicylic acid [olsalazine (OLZ)] was developed for colon-specific drug delivery. These copolymers contained azo bonds that would be degraded by the azoreductase activities in the colon. The resultant condensation polymers were characterized with Fourier transform infrared, nuclear magnetic resonance, and gel permeation chromatography. The degradation behavior of the polymer was evaluated in vitro and in vivo. The in vitro results indicated that the active 5-aminosalicylic acid (5-ASA), one of the degradation products, could be released in the medium of the cecum contents specifically. In an in vivo test, there was a 8-h lag time before 5-ASA could be detected in urine samples, and this indicated that the conjugate could remain intact in the upper part of the gastrointestinal tract. In comparison with OLZ, the release profiles of 5-ASA from PEG–OLZ copolymers were significantly prolonged. In addition, the release profiles of 5-ASA from PEG–OLZ copolymers could be adjusted by changes in the molecular weight of the PEG segment. Because of these advantages of PEG–OLZ copolymers, it could be concluded that PEG–OLZ copolymers could be promising candidates for colon-specific polymeric prodrugs of 5-ASA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Nitrogen/sulfur-co-doped mesoporous carbon (Phen-HS) was obtained through direct carbonization of a single protic salt, that is, 1,10-phenanthrolinium dibisulfate ([Phen][2 HSO4 ]), in the presence of a colloidal silica template without the use of additional acid or metal catalysts for prepolymerization prior to carbonization. Phen-HS was prepared in a relatively high yield (30.0 %) and has a large surface area (1161 m(2) g(-1) ), large pore volume (2.490 cm(3) g(-1) ), large mesopores (≈12 nm), narrow pore-size distribution (7-16 nm), and high nitrogen (7.5 at %) and sulfur (1.3 at %) contents. The surface area/pore-size distribution is much higher/narrower than that of most reported carbon materials obtained from traditional precursors by using the same template. Phen-HS was directly used as an electrocatalyst for the oxygen reduction reaction (ORR) and as an electrode material for supercapacitors. As an efficient metal-free catalyst, Phen-HS exhibited good electrocatalytic activity toward the ORR in a 0.1 M KOH aqueous solution, which is comparable to the activity of a commercial Pt/C catalyst. Electrochemical measurements for Phen-HS used in a double-layer capacitor showed high specific capacitances of 160 and 140 F g(-1) in 1 M H2 SO4 and 6 M KOH, respectively, with good rate capabilities and high cycling stabilities.

Chemoselective hydrogenation of aromatic nitro compounds were first efficiently achieved over Au/Fe(OH)(x) at 100-120 degrees C for 1.5-6 h (depending on different substrates) in the presence of CO and H(2)O.