LANGMUIR
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2019
·
IF 3.683
Zidong Zhang,Yuming Tu,Hui Yu,Weidong Liu,Zhiyong Zhou,Zhongqi Ren
Extraction is a common approach to separating aromatics and alkanes, but solvent recovery remains an issue. The polarity, hydrophobic/hydrophilic balance, and other properties of switchable solvents can be reversibly changed in the presence of various triggers, and taking advantage of this property can greatly simplify the process of solvent recovery. In this work, quaternation and anion exchange were used to prepare several switchable solvents by introducing OH– ions to derivatives of the amidine compound 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The resulting compounds exhibited reversible switching in response to exposure to CO2. Using toluene/n-heptane as a model hydrocarbon mixture, a reversible phase change extraction process was established. Among the four switchable solvents prepared, [C2DBU]OH showed the highest selectivity value and so was used to investigate the effect of various parameters on hydrocarbon separation. The extraction process was found to rapidly reach equilibrium when a two-phase system was generated by bubbling CO2 through the extraction mixture. Increasing the proportion of the solvent increased the selectivity for toluene, while a 1:1 ratio between the solvent and the toluene/n-heptane mixture enhanced the extraction. Increasing the initial toluene concentration reduced the selectivity for toluene, with a value of 5.97 at a toluene concentration of 20%. The switchable solvent recovered its initial state when heated at 60 °C for 1 h. Upon being reused after removal of CO2, the solvent exhibited poor separation characteristics, although the selectivity coefficient remained constant at approximately 3.1 during 10 regenerations. Finally, the mechanism of the switchable solvent effect and modeling of experimental data were investigated.
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高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
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IF 4.784
Xinxin Yang,Zhaoshuang Li,He Liu,Lina Ma,Xujuan Huang,Zhaosheng Cai,Xu Xu,Shibin Shang,Zhanqian Song
N-vinylcaprolactam (NVCL) is a temperature-responsive monomer, which is widely used for preparing responsive hydrogels. However, poor water solubility of NVCL necessitates the use of emulsifiers for better dispersion. Hydrolyzed epoxy soybean oil-grafted hydroxyethyl cellulose (H-ESO-HEC) polymeric emulsifier has excellent emulsifying properties, and the carboxyl groups afford pH-responsiveness to the hydrogels. A novel temperature- and pH-responsive cellulose-based hydrogel was prepared by combining NVCL and H-ESO-HEC. The hydrogel morphology, thermal stability , and swelling capacity were characterized, and it was also used as a dual-responsive drug preservative carrier. Scanning electron microscopy and thermogravimetric analysis confirmed the porous structure and good thermal stability, respectively, of the hydrogel. The hydrogel displayed a temperature- and pH-dependent swelling behavior and improved swelling capacity. The swelling behavior agreed well with the Korsmeyer-Peppas model and Schott's second-order kinetic model. The dual-responsive hydrogel has significant potential in the drug delivery systems owing to its biocompatibility and temperature and pH sensitivity.
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ACS Applied Materials & Interfaces
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2019
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IF 8.456
Guo Ye,Zizheng Song,Tianhao Yu,Qishuo Tan,Yan Zhang,Tinglei Chen,Changcheng He,Lihua Jin,Nan Liu
Stretchable conductors have been achieved by stacking conductive nanomaterials onto the surfaces of elastomeric substrates. However, many of them show a dramatic decrease in conductivity under strain without an efficient way for the conductive layer to release strain. Here, we report a transparent, stretchable, and self-healing conductor with excellent mechanoelectrical stability by introducing dynamic bonding between conductive nanomaterials and an elastomeric substrate. We prepare the conductor by semiembedding Ag nanowires (AgNWs) into a self-healing polydimethylsiloxane (PDMS)-based elastomer, which is modified with bipyridine (Bpy) ligand and further cross-linked by adding Zn2+ as coordinator (Zn–Bpy–PDMS). The dynamic Ag–N bonds not only improve the wettability of the substrate and facilitate the spreading of AgNWs but also reversibly break and reform to accommodate the deformation of AgNWs. As a result, the resistance increase of Zn–Bpy–PDMS/AgNWs is much smaller than that without the dynamic bonding (PDMS/AgNWs). Besides, this conductor exhibits excellent conductivity (76.2 Ω/sq) and transparency (86.6% @ 550 nm), as well as extraordinary self-healing property with a low resistance increase (ΔR/R0 ∼ 1.4) after healing at room temperature for 1 day. This work provides insights into the future design of integrated electronic skin with transparency, stretchability, conductivity, and self-healing capability for applications in wearable optoelectronic devices.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
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IF 4.084
Mengya Guo,Li Wang,Yuying Gao,Guozhu Li
Doping carbon materials with Fe and N attracts great attention due to its promising application in preparing ORR electrode with high performance and low cost. Previously, Fe, N-codoped catalyst (Fe/N/C) had been synthesized via a simple one-pot method using carbon materials, dopamine and FeCl 3 by our group. However, the unstable activity and low selectivity (electron transfer number of ∼3.5) are key problems that should be solved. Herein, trace sulfur has been introduced into Fe, N-codoped carbon black by using 2-mercaptoethanol as an adhesive sulfur precursor. By the doping of trace S atoms (∼0.25 at%) into Fe, N-codoped carbon frameworks, the ORR performance has been obviously improved simply without any re-treatment process, such as acid-etching or nitrogen supplement. The mechanism of this process has been systematically investigated by changing the amount of initial sulfur precursor. A moderate amount of trace sulfur can effectively enhance the ORR performance of Fe, N-codoped carbon black due to suitable interactions among Fe, N, S and C elements. Both the content and the state of Fe and N species on the surface of carbon black can be changed and controlled by trace sulfur. The as-synthesized 1.0 S Fe/N/C catalyst exhibits a good ORR activity (E 1/2 = 0.749 V, J k = 54.56 mA cm −2 ) and a total 4-electron selectivity. 1.0 S Fe/N/C also shows better catalytic stability and methanol tolerance than 20 wt% Pt/C.
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Journal of Materials Chemistry C
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2019
·Vol. 7
·期 11
·3181-3189
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IF 6.641
Xin Cheng,Lin Wang,Fengmei Gao,Weiyou Yang,Zhentao Du,Ding Chen,Shanliang Chen
The third-generation semiconductor silicon carbide (SiC) is identified as one of the vitally important candidate materials to serve as a functional unit that performs stably and reliably under harsh working conditions, with respect to its excellent piezoresistive effects and robust physical/chemical characteristics. In the current work, we put forward the fabrication of SiC nanowires with co-doped N and P elements, which were fabricated via the pyrolysis of a polymeric material. The as-grown nanowires have a typical diameter of ∼260 nm with a 10 surface. The measured transverse piezoresistance coefficient π[10] of the established SiC nanowires increased from 5.07 to −146.30 × 10−11 Pa−1 as the loading forces varied from 24.95 to 130.51 nN. Meanwhile, the corresponding gauge factor (GF) was calculated up to ca. −877.79, which is higher than the values for all SiC nanostructures ever reported. The mechanism concerning the giant negative piezoresistance behavior of SiC nanowire is proposed. The current exploration may pave a new avenue for the development of highly sensitive and robust pressure sensors that could survive under harsh working conditions.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Shihang Guo,Yi Feng,Jianhao Qiu,Xiaodan Li,Jianfeng Yao
Transition metal sulfides have attracted wide attention in energy storage, especially in Li-ion batteries anodes due to the high theoretical capacity and low cost. However, their poor stability and rate performance have hindered their further development. Here, leaf-shaped ZIF (zeolitic imidazole framework) was used as precursor to prepare two-dimensional (2D) CoZnS x @N-doped Carbon (L-Co 2 Zn 1 -S) to address this problem. The different distribution of Zn 2+ and Co 2+ will greatly influence the morphology of products. L-Co 2 Zn 1 -S displays great cycling performance of specific capacity of 527 mA h g −1 at 0.5 A g −1 after 200 cycles with Coulombic efficiency of about 99% and excellent rate capability as lithium-ion battery anode. This superior electrochemical performance can be ascribed to 2D N-doped carbon structure and synergistic effect of bimetallic sulfide. This work not only casts a new light on the design of bimetallic sulfides but also provides a manufacturing method of 2D carbon matrix.
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FUEL
·
2019
·
IF 5.128
Xiaojie Li,Erjiang Hu,Xin Lu,Shihan Huang,Zuohua Huang
Laminar flame speeds of hexene isomers (1-hexene, 2-hexene and 3-hexene) and n-hexane are investigated at equivalence ratios of 0.8–1.5, initial temperatures of 373–453 K and initial pressures of 0.1–0.5 MPa using a constant volume combustion chamber . Results show that laminar flame speeds of hexene isomers are similar to each other and higher than those of n-hexane. NUI model, Fan model and LLNL model are validated against the experimental data. Simulation results of NUI model and Fan model agree well with experimental data while results of LLNL model show large discrepancies. The discrepancies between hexene isomers and n-hexane are mainly caused by thermal effect. Reaction pathway analysis shows that hexene isomers undergo similar reactions including H-abstraction reactions, radical-addition reactions and unimolecular decomposition reactions . Sensitivity analysis also reveals that the sensitivity coefficients of fuel specific reactions of hexene isomers are close to each other on the whole.
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INTEGRATED FERROELECTRICS
·
2019
·
IF 0.486
Chengyi Chu,Huangsheng Wu,Aihua Sun,Xiaobing Tang,Yugang Yan,Guoxiong Shao,Zhixiang Li,Jianjun Guo,Gaojie Xu
The multresponsive photonic hydrogels (MRPHs) based on Fe3O4@C NPs and Acrylamide-N-isopropylacrylamide (AM-NIPAM) was prepared by UV polymerization process with the help of magnetic field. This work is mainly about the long-term stability of MRPHs. The mechano-response performance of MRPHs after being remained in water for a year has been measured and discussed in details. The result shows that the MRPHs were still very sensible and exhibit brilliant structure color. The reflectance peak of MRPHs changed markedly (from 700 nm to 550 nm) as increasing compression from 0 to 1N and the structure color change can be made reversible for ∼100 times or even more if necessary. Besides, the structure color of MRPHs was broken after being natural air-dried for 3 months and it can recover when dried MRPHs were immerged in water for 10 hours. So the MRPHs have good stability and the structure color can persevere for long time without fading, which contributes to the piratical application of MRPHs used as sensors.
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Jinhe Shu,Qijian Niu,Nannan Wang,Jun Nie,Guiping Ma
Exploring biomass-derived non-precious metal carbon-based electrocatalysts have attracted intensive interest in the field of energy conversion due to their low-cost, ecofriendly and sustainable. Herein, we report a novel strategy for preparation of Co/N doped hierarchical porous carbon microspheres (Co/NHPCMS), via pyrolysis ZIF-67@SA/NaHCO 3 microspheres prepared by in-situ growth of ZIF-67 on electrospray Co-SA/NaHCO 3 microspheres. ZIF-67 nanocrystals were well distributed on the ions cross-linked alginate/NaHCO 3 microspheres. The pyrolysis of ZIF-67@SA/NaHCO 3 microspheres could provide abundant active sites and rich porous structure. More importantly, NaHCO 3 plays an essential role in obtaining large mesopores and high pore volume , which is benefit to facilitate the diffusion of reactants. With these merits, Co/NHPCMS-600 exhibits an outstanding ORR electrocatalytic performance with a half-wave potential of 0.827 V. Besides, Co/NHPCMS-600 catalyst exhibits superior catalytic stability and tolerance to methanol in the ORR. This work provides a promising route based on sustainable biomass toward high performance electrocatalyst in the field of energy conversion.
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LANGMUIR
·
2019
·
IF 3.683
Lunqiang Jin,Xiang Zhang,Weifeng Zhao,Shengqiu Chen,Zhenqiang Shi,Jingxia Wang,Yi Xie,Feng Liang,Changsheng Zhao
Applications of effective and steady metal catalysts for the hydrogen evolution reaction (HER) via electrolysis of water have a huge potential to relax energy crisis and reduce carbon dioxide emission. Herein, we design a simple, facile, and general approach for the synthesis of a series of transition-metal phosphide nanoparticles embedded in N-doped carbon (NC) nanomaterials using metal salts, abundantly available hexamethylene diamine tetra(methyl phosphonic acid), and urea as precursors. The resultant transition-metal phosphide nanoparticles can serve as high-efficiency and steady HER catalysts. Particularly, when the current density is 10 mA cm–2, the overpotentials of the obtained RhP2@NC are 30, 85, and 70 mV in acid (0.5 M H2SO4), neutral (1 M PBS), and alkaline (1 M KOH) solutions, respectively. Besides, the RhP2@NC exhibits good stability after 10 h in aforementioned solutions. More importantly, it is suited to fabricate other transition-metal phosphide nanoparticles/NC heterostructures by this synthetic strategy. The obtained CoP@NC, FeP@NC, Ni2P@NC, and Cu3P@NC also show relatively high efficiency for HER. Hence, the versatile synthesis strategy opens a new route for the research and fabrication of transition-metal phosphide-based catalysts for HER.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Xiaoyan Liu,Guojun Lan,Yash Boyjoo,Lihua Qian,Sai Gu,Cameron Alexander Hurd Price,Liang Wang,Ying Li,Jian Liu
Ru/carbon catalyst has been considered as a very active catalyst in aqueous-phase hydrogenation of bio-resourced carbonyl compounds. High dispersion of Ru NPs on a carbon support could enhance catalytic performance. In this work, well dispersed Ru nanoparticles on the surface of carbon spheres have been developed by the introduction of nitrogen-doping. Compared with carbon spheres without N-doping, the incorporation of the N-dopant with in the carbon matrix effectively improved the dispersion of Ru nanoparticles, which was confirmed by X-ray photoelectron spectroscopy (XPS) and CO chemisorption characterizations, finding that the presence of quaternary N was responsible for the high dispersion of Ru nanoparticles. Through adjusting the carbonization temperature from 400 to 850 °C, we have shown that the absolute content of quaternary N can be modulated from 3.2 to 22.4 mg g −1 . As a result, the dispersion of Ru nanoparticles was improved from 29.8% to 70.9%. The Ru/N-CS-850 catalyst revealed excellent catalytic performance (9858 h −1 turnover frequency) for the hydrogenation of levulinic acid to γ-valerolactone, also demonstrated very high catalytic activity for other hydrogenation reactions.
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JOURNAL OF LUMINESCENCE
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2019
·
IF 2.961
Yan Hua,Daocheng Hong,Sushu Wan,Yanyu Lei,Mingcai Xie,Weiqing Yang,Yu Du,Yuxi Tian
2D perovskite materials have attracted increasing attention in the last few years due to their optical tunability. However, how to control the structure of these materials is still one of the key challenges. In this work, by using photoluminescence microscopy and XRD characterization, we found that ethanol treatment can induce the reorganization of the crystal structure of 2D perovskite materials. The ethanol molecules can insert into (OA) 2 (MA)Pb 2 I 7 (OA = CH 3 (CH 2 ) 7 NH 3 ; MA = CH 3 NH 3 ) crystal lattice and preferentially dissolve MA ions reducing the MA/OA ratio. During the recrystallization, new (OA) 2 PbI 4 phase forms due to the low MA/OA ratio. On the other hand, adsorption of ethanol can induce the photoluminescence (PL) enhancement by passivation of the surface defects . Consequently, PL intensity increases and decreases as the activation/deactivation of the quenching defects. These results provide a possible way to optimize the crystal structure of 2D perovskite under mild condition.
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