Royal Society Open Science
·
2019
·Vol. 6
·期 8
·
IF 2.515
Ran Liu,Ke Zhang,Chen Liu,Yanhui Hu,Lilong Zhou,Juan Zhang
Four kinds of functional ionic liquids (ILs) ([C3SO3Hnmp]HSO4), 1-(3-sulfopropyl)-1-methylpyrrolidone phosphate ([C3SO3Hnmp]H2PO4), 1-(3-sulfopropyl)-1-methylpyrrolidone p-toluene sulfonate ([C3SO3Hnmp]CH3SO3H) and 1-(3-sulfopropyl)-1-methylpyrrolidone methyl sulfonate ([C3SO3Hnmp]C6H6SO3H)) were prepared and the catalytic activity of these ILs during esterification of carboxylic acids (formic acid, acetic acid, propionic acid, butyric acid) with alcohols was investigated. The results indicated that the IL ([C3SO3Hnmp]HSO4) exhibited an optimal catalytic performance. And then the IL ([C3SO3Hnmp]HSO4) was immobilized to the silica gel. The immobilized IL performed more excellent catalytic activity than the unsupported [C3SO3Hnmp]HSO4. The effects of reaction temperature, reaction time, molar ratio of acid to alcohol and catalyst dosage were investigated. The response surface methodology based on the Box–Behnken design (BBD) was used to explore the best reaction condition of different experimental variables. Accordingly, a high n-butyl butyrate yield of 97.10% under the deduced optimal reaction conditions was obtained, in good agreement with experimental results and that predicted by the BBD model. The immobilized IL [C3SO3Hnmp]HSO4 maintained high catalytic activity after five cycles.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2018
·Vol. 135
·期 25
·46375
·
IF 1.901
Zhixin Xiao,Yun Tan,Jianjun Ma,Di Wang,Lina Yu,Fan Yue,Shimei Xu,Jianbin Huang
A facile method was explored to synthesize thermosensitive poly[ N -isopropylacrylamide (NIPAM)- co -methacryloxyethyltrimethyl ammonium chloride (DMC)]/Na 2 WO 4 cationic hydrogels via copolymerization of NIPAM and DMC in the presence of Na 2 WO 4 . Na 2 WO 4 acted as both a physical crosslinking agent and a porogen precursor. The hydrogels were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray, thermogravimetry, environmental scanning electron microscopy, and transmission electron microscopy. Effects of various salt solutions, pH solutions on swelling were investigated. Thermosensitivity of the hydrogels were also investigated in various polar solvents at different temperatures. The resultant hydrogel showed a fast swelling rate and good salt tolerance. The hydrogels reached the swelling equilibrium within 10 min. Moreover, the swelling ratio of the hydrogels increased with the increase of the polarity of the solvent. In the water, the swelling ratio decreased with the increasing of temperature, but remained at a high level even at 80 °C since the pore structure weaken the lower critical solution temperature effect of PNIPAM. The swelling ratio increased instead in low polar solvent, while it became negligible in nonpolar solvent with the increasing of temperature. The whole swelling kinetics was fit for Schott's pseudo-second order model. The hydrogels have a great potential as catalysts and smart materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46375.
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Soft Matter
·
2018
·Vol. 14
·期 10
·1789-1798
·
IF 3.709
Yaping Zhang,Jingwen Ji,Haiping Li,Na Du,Shue Song,Wanguo Hou
Nanocomposite (NC) hydrogels of positively charged layered double hydroxide (LDH) single-layer nanosheet (SLNS) cross-linked poly(N-isopropylacrylamide) (PNIPAM) were synthesized. Especially, the LDH SLNSs used here were pre-synthesized via an aqueous synthetic route without using organic solvents and modifiers. The obtained LDH/PNIPAM NC hydrogels were characterized using XRD, SEM, TEM, and DSC. The mechanical and thermoresponsive properties were determined using tensile, compression, and swelling/deswelling tests. Interestingly, different network structures are observed for the NC hydrogels along the horizontal and vertical directions; those along the horizontal direction exhibit a fine and uniform sponge-like network structure while those along the vertical direction exhibit a hierarchical layered architecture. Compared with the conventional N,N′-methylene bisacrylamide cross-linked PNIPAM hydrogel, the NC hydrogels exhibit extraordinary deformability and stretchability and obviously improved thermoresponsive swelling/deswelling characteristics. Furthermore, the fracture elongation observed here is obviously higher than those reported for negatively charged clay/PNIPAM NC hydrogels. With the increase in the LDH content from 0.8 to 2.0 wt%, the fracture strength and the compressive strength at an 85% strain increase from 23.5 to 37.2 kPa and from 0.15 to 0.57 MPa, respectively, while the fracture elongation decreases from 2689 to 2202%. The mechanism for the improved mechanical performances of the NC hydrogels is discussed. To the best of our knowledge, this is the first report on LDH/PNIPAM hydrogels. This work provides a green synthesis route for LDH-containing NC hydrogels. The new NC hydrogels may have great potential applications such as in tissue engineering, drug vehicles, and sorbents.
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ChemPlusChem
·
2018
·Vol. 83
·期 11
·1044-1051
·
IF 3.205
Mengxin Zhang,Dan Wu,Yingxiang Ye,Ling Wu,Zizhu Yao,Xiuling Ma,Lihua Wang,Zhangjing Zhang,Shengchang Xiang
Graphical Same but different : Two isomorphic metal−organic frameworks (MOFs) [FJU-40-H ( a ) and FJU-40-NH 2 ( b )] were used to construct core−shell materials MOF@MOF. This strategy has resulted in an N-doped porous carbon material that displays high catalytic activity for the oxygen reduction reaction (ORR). Here we propose a new strategy in which two isomorphic metal−organic frameworks (MOFs) [FJU-40-H ( a ) and FJU-40-NH 2 ( b )] are used to construct the core-shell material MOF@MOF. This strategy based on nitrogen doping and specific surface has resulted in an N-doped porous carbon (NPC) material in a one-step thermal treatment in N 2 atmosphere; this material displays high catalytic activity for the oxygen reduction reaction (ORR). The materials were analyzed by SEM, XPS, Raman, specific surface area, pore size distribution and electrochemical measurements. It was found that NPC derived from the core-shell MOF@MOF can provide excellent catalytic ORR performance exceeding that of the single MOF. The onset potential is NPC-b@a-4h (−0.068 V)>NPC-a@b-4h (−0.075 V)>NPC-a-4h (−0.109 V)>NPC-b-4h (−0.113 V). Moreover, the results also show that the performance of NPC-b@a (n=4.15) is better than that of NPC-a@b (n=3.32), which means the different nitrogen content of ligands inside and outside of the core affects the ORR properties.
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Journal of Energy Chemistry
·
2018
·
IF 3.886
Jie Yin,Binbin Wei,Yuxuan Li,Yefei Li,Pinxian Xi
Achieving high activity and stability oxygen evolution reaction (OER) catalysts to optimize the efficiency of metal−air battery , water splitting and other energy conversion devices, remains a formidable challenge. Herein, we demonstrate the metallic porous nanowires arrays with abundant defects via nitrogen and copper codoped CoS 1.97 nanowires (N−CuCoS 1.97 NWs). The N−CuCoS 1.97 NWs can serve as an excellent OER self-supported electrode with an overpotential of 280 mV ( j = 10 mA cm −2 ) and remarkable long-term stability. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectrum (XPS) measurements confirmed the surface lattice oxygen created on the N−CuCoS 1.97 NWs during OER. Then, the density function theory (DFT) results evident that lattice oxygen constructed surface of N−CuCoS 1.97 NWs has more favorable OER energetic profiles and absorption for reaction intermediate. More importantly, the flexible and wearable Zn−air battery fabricated by the N−CuCoS 1.97 NWs shows excellent rechargeable and mechanical stability, which can be used in portable mobile device.
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ORGANIC ELECTRONICS
·
2018
·
IF 3.68
Xiao Gong,Wenwen Ma,Yunxia Li,Lingqi Zhong,Wenjing Li,Xiujian Zhao
Luminescent solar concentrators (LSCs) as alternatives to solar cells are suitable for photovoltaic windows. Generally semiconductor quantum dots are employed as emitters for LSC fabrication due to their advantages such as photostability, spectral tunability, and high photoluminescence quantum yield . In this paper, we used low cost and environmentally friendly N-doped carbon-dots (N-CDs) as phosphors to fabricate N-CDs/PMMA slab based luminescent solar concentrators. The high-performance N-CDs/PMMA slab based LSCs with an external optical efficiency of 12.23% could be achieved when the concentration of N-CDs within the PMMA matrix is 0.08 wt%. Our results showed that N-CDs/PMMA slab based luminescent solar concentrators make the practical use of LSCs more feasible because of the unique properties of N-CDs.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
·
IF 4.229
Ruijing Wang,Peng Sun,Huanwen Wang,Xuefeng Wang
Development of highly-active and noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is of critical challenge for water splitting, and optimizing the structure and the composition of the relative materials is very necessary to obtain the high-quality catalysts. Herein, a novel molybdenum carbide/N-doped carbon (Mo 2 C/NC) hybrid is fabricated by using the hierarchical polyaniline tube network as a carbon source and a reactive template, and the as-fabricated Mo 2 C/NC hybrid possesses a uniform hierarchical tube structure. The coupling of the ultrafine Mo 2 C nanoparticles and the N-doped carbon substrate provides the abundant active sites and accelerates the charge transfer process. The final Mo 2 C/NC catalyst gives the excellent catalytic activity for HER in alkaline condition, which shows a lower overpotential of 142 mV at 10 mA cm −2 and a small Tafel slope of 61 mV decade −1 in 1 M KOH.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Ting Lü,Dongming Qi,Dong Zhang,Shanshan Lin,Yanran Mao,Hongting Zhao
In this study, a class of N-(aminoethyl)-aminopropyl functionalized core-shell magnetic nanoparticles (MNPs) was fabricated for emulsified oil-water separation. Fe 3 O 4 MNPs were synthesized by using a solvothermal method, followed by surface coating with N-(aminoethyl)-aminopropyl functionalized silica (AEAPFS) layer to improve its chemical stability, surface charge and interfacial activity. The synthesized MNPs were characterized by various technologies and their oil-water separation performances were evaluated under various conditions. Although Fe 3 O 4 MNPs had negligible oil separation efficiency, the AEAPFS-coated MNPs (Fe 3 O 4 @AEAPFS MNPs) exhibited satisfactory oil-water separation performance at various pH levels. Results showed that, under both acidic and neutral conditions, positively charged Fe 3 O 4 @AEAPFS MNPs could effectively adsorb onto oil droplets via electrostatic attraction and interfacial activity; while under alkaline condition, negatively charged MNPs could overcome electrostatic repulsion and absorb onto oil droplet via hydrophobic interaction, thereby facilitating subsequent magnetic separation. Moreover, the synthesized Fe 3 O 4 @AEAPFS MNPs could be recycled up to 5 cycles without showing significant loss in separation efficiency. In conclusion, Fe 3 O 4 @AEAPFS MNPs can be easily synthesized and recycled, providing a simple but powerful approach for emulsified oil-water separation.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Mengchen Wu,Xianxiang Hu,Congling Li,Jian Li,Haijun Zhou,Xia Zhang,Rui Liu
High-performance non-precious metal-doped carbon catalysts for oxygen reduction reactions (ORR) are viable candidates in lieu of platinum-based catalysts. It has been universally reported that active Co–N sites combined with Fe–N sites embedded in carbon matrix represent the most promising active sites for ORR process. Benefiting from the cage-encapsulated-precursor pyrolysis strategy, herein, we fabricated a Fe–N and Co–N homogeneously doped carbon framework by one step. TEM demonstrated the ultimate product had well-defined morphology with Fe (0.54 at%), Co (0.31 at%) and N (2.94 at%) uniformly distributed into the carbon skeleton. The N 2 absorption-desorption isotherms indicated the MOF-derived catalyst had a high specific surface area of 647.6 m 2 g −1 and inherit hierarchical porosity . Significantly, such FeCo–NC catalyst outperformed a current density (5.6 mA cm −2 ) at 0.70 V (vs reversible hydrogen electrode) 1.18 times higher than that of a commercial 20 wt% Pt/C (5 mA cm −2 ) catalyst in alkaline medium , and more positive peak potential of 0.63 V than its counterparts. Its high cycling stability and immunity towards methanol crossover in a wide range pH value showed good potential to be used as cathodes in proton exchange membrane fuel cells (PEMFCs) for long term operation. This simple synthesis strategy would to some degree leverage a cage-encapsulated-precursor for tailored utility of active sites for ORR in a porous carbon framework.
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ENERGY
·
2018
·
IF 4.968
Zhishan Zhang,Guruprasad Alva,Min Gu,Guiyin Fang
In this work, polystyrene–based form–stable composite phase change materials (CPCMs) were fabricated by a solution and reflux method. In the composites, the n–octadecane (ODE) was used as thermal energy storage material, the polystyrene (PS) acted as the supporting material, and expanded graphite (EG) was employed as thermal conductive filler to improve the thermal conductivity of the composites. The toluene was adopted as solvent. Both polystyrene and n–octadecane smoothly dissolve in toluene. EG was also easily dispersed into the matrix. CPCMs were obtained after distillation of the toluene. The differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA) were adopted to assess the thermal properties and thermal stability of the CPCMs, respectively. Fourier transformation infrared (FT–IR) spectroscope and scanning electronic microscope (SEM) were utilized to determine the chemical structure and microstructure of the ODE/PS/EG composites. The thermal conductivity of the CPCM with 5 wt% content of EG can reach up to 1.01 W/m·K, which is nearly 7 times higher than that of the CPCM without the EG. The latent heat value of CPCM with the highest ODE content (48.5 wt%) is 98.05 J/g, the melting temperature is 27.5 °C, which is close to room temperature. Therefore, the form–stable CPCMs are promising thermal energy storage materials in solar thermal energy storage systems , such as solar heating system in buildings.
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JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Fan Hu,Zhanghui Wang,Baoku Zhu,Liping Zhu,Youyi Xu
Energy-efficient and time-saving process for recovery of hazardous dyes from wastewater is highly desired in dyeing industry. In this work, poly( N -vinyl imidazole) (PVI) gel-filled membrane adsorbers were developed for highly efficient recovery of dyes through adsorption filtration. The membrane adsorbers were fabricated via dip-coating of Nylon macroporous membranes in PVI solutions followed by quaternization crosslinking with p-xylylene dichloride (XDC). Physicochemical characterizations indicated that PVI gel was successfully filled and fixed inside the Nylon matrix. In optimized conditions. The treating capacity of membrane adsorbers to typical dye sunset yellow (25 ppm of the feed concentration) reached up to 197 mg/g with the removal ratio >99%. Both the treating capacity and the removal ratio were kept steady even when the permeation flux was as high as 1000 L/m 2 h. The membrane adsorbers developed in this work were able to not only remove anionic dyes from water, but also separate anionic dyes from cationic ones. The zeta potential and adsorption tests showed that the electrostatic interaction between PVI gel and dye molecules was responsible for the high removal efficiencies to anionic dyes. The membrane adsorbers can be regenerated effectively with NaOH solution and demonstrated good stability in both acidic and alkaline conditions.
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Polymers
·
2018
·Vol. 10
·期 3
·293
·
IF 2.935
Jiaxing Li,Lei Yang,Xiaoguang Fan,Fei Wang,Jing Zhang,Zhanyong Wang
Continuing efforts to develop novel smart materials are anticipated to upgrade the quality of life of humans. Thermo-responsive poly(N-isopropylacrylamide) and glucose-responsive phenylboronic acid—typical representatives—are often integrated as multi-stimuli-sensitive materials, but few are available for side-by-side comparisons with their properties. In this study, both copolymers bearingN-isopropylacrylamide (NIPAAm), with or without 3-acrylamidophenylboronic acid (AAPBA), were synthesized by free radical polymerization, and characterized by Fourier transform infrared spectrometry, nuclear magnetic resonance hydrogen spectroscopy and gel permeation chromatography. Dynamic light scattering was used to analyze and compare the responsive behaviors of the copolymers in different aqueous solutions. Atomic force microscopy was also employed to investigate the apparent morphology changes with particle sizes. The results demonstrated that the introduction of NIPAAm endowed the composite materials with thermosensitivity, whereas the addition of AAPBA lowered the molecular weight of the copolymers, intensified the intermolecular aggregation of the nanoparticles, reduced the lower critical solution temperature (LCST) of the composites, and accordingly allowed the copolymers to respond to glucose. It was also concluded that the responding of smart copolymers to operating parameters can be activated only under special conditions, and copolymer dimension and conformation were affected by inter/intramolecular interactions.Keywords:poly(N-isopropylacrylamide);phenylboronic acid;smart responsive behavior;hydrodynamic diameter;dynamic light scattering
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