JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Gang Shao,Junfang Liang,Wanyu Zhao,Biao Zhao,Wen Liu,Hailong Wang,Bingbing Fan,Hongliang Xu,Hongxia Lu,Yiguang Wang,Rui Zhang
Ultra-wide absorption bandwidth is one of the goals of ideal absorbing materials. In this article, three-dimensional porous microstructure Co/SiCN ceramic aerogel composites (CACs) were synthesized through a reverse microemulsion method, which is aimed to avoid the aggregation of cobalt nanoparticles , and makes better impedance matching between CACs surface and air to obtain an outstanding microwave absorption (MA) performance. The complex permittivity of the CACs could be tuned via the concentration of cobalt acetate solution. The MA results indicate that CACs with cobalt acetate solution concentration of 0.5 mol/L shows an excellent MA properties with ultrabroad bandwidth 8.5 GHz covering the whole K band (18–26.5 GHz). The excellent MA performance can be attributed to good impedance matching, multiple reflections, polarization processes, and the synergistic effects in the CACs. Therefore, our study paves a novel way to fabricate the promising lightweight MA materials with ultrabroad absorption bandwidth at higher frequency.
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高影响因子
POLYMER
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2019
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IF 3.771
Longfei Li,Hong Zhai,Tao Wang,Xibo Qiu,Na Qiang,Peng Dong,Ying Bai,Ai-Yun Peng,Daping Quan
The ring-opening copolymerization of lactide with carbonate is an available strategy to incorporate reactive groups to the pendent sites of copolymer for further functional modification. A series of random and block copolymers were synthesized from l -lactide ( L -LA) and 2-bromomethyl-2-methyltrimethylene carbonate (BMTC) using dodecanol as initiator and stannous octoate as catalyst. The structures of the copolymers were characterized by nuclear magnetic resonance ( 1 H NMR, 13 C NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The composition of the copolymers can be controlled through changing the feed ratios of n BMTC / n L -LA . It was found the random P(BMTC- co - L LA) copolymers had the semicrystalline characteristic due to the relative long block-like segments of P L LA ( L L , P L LA = 5.3–7.3) and the polar interactions from bromo groups , but their crystallinity ( X c, P L LA ) and melting temperature ( T m, P L LA ) decreased when the BMTC content increased. The X c, P L LA and T m, P L LA of P(BMTC- b -P L LA) block copolymers were relatively higher than the corresponding random copolymers, and approached gradually to the pure P L LA with the increase of the molecular weight of P L LA block. Finally, the pendent bromo groups of P(BMTC- co - L LA) were easily transformed into azides , which could proceed the azide-alkyne click reaction smoothly and quantitatively at room temperature .
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JOURNAL OF CATALYSIS
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2018
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IF 6.759
Xiaobin Dong,Songlin Chao,Fanfan Wan,Qingxin Guan,Guichang Wang,Wei Li
Acetylene hydrochlorination is a major technology for producing vinyl chloride in coal-rich areas, but its development is restricted by its utilizing the toxic mercury chloride (HgCl 2 ) catalyst. Lately, several nitrogen-doped carbon materials have been studied and are considered to be a feasible alternative. Here, we propose an approach based on sulfur doping to effectively improve the pyridinic N content in N-doped carbon material. According to high-resolution XPS and C 2 H 2 TPD results, C atoms adjacent to pyridinic N were proved to be active sites, and thus the co-doped carbon catalyst exhibited a higher acetylene conversion than the N-doped carbon sample. Furthermore, the co-doped catalyst processed in NH 3 exhibits preferable catalytic activity and competitive stability owing to its high specific surface area, mesoporous structure, and high nitrogen level. Good performance, combined with the features of low cost and ecofriendliness, makes sulfur and nitrogen co-doped carbon a promising catalyst for acetylene hydrochlorination.
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高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
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2018
·Vol. 36
·期 9
·1063-1069
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IF 2.016
Chen Lu,Cheng Hui-Hui,Xiong Jiang,Zhu Ya-Ting,Zhang Hong-Peng,Xiong Xi,Liu Yu-Man,Yu Jian,Guo Zhao-Xia
Gelatin, a natural proteinous polymer, was used to co-electrospin with poly(butylene succinate) (PBS) in order to improve the mechanical properties of PBS membrane and facilitate its applications in biomedical field. The PBS/gelatin blend membranes have narrower distribution of fiber diameter and smoother surface than neat PBS membrane. The contact angles, water absorption rates and water uptakes of the PBS/gelatin blend membranes were measured, showing increased hydrophilicity. The interaction between PBS and gelatin was investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC). The mechanical properties of PBS/gelatin blend membranes in both dry and wet states were evaluated by uniaxial tensile tests. In the dry state, the PBS/gelatin blend membrane containing 10% gelatin has a 3-times increase in tensile strength without any adverse effect on ductility because of the existence of interaction between the two blend components, little change in crystallinity of PBS, and possible interaction between any adjacent fibers; the tensile strength and elongation at break are even better in the wet state attributed to some gelatin on fiber surfaces, which act as a binder in the presence of water. The potential applications of PBS/gelatin blend membranes were demonstrated by successful immobilization of thrombin, a clinically-used hemostatic drug. The thrombin-loaded membrane could be used for rapid hemostasis.
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高影响因子
CERAMICS INTERNATIONAL
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2018
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IF 3.057
Qiang Liu,Jinbang Li,Jiawei Dai,Zewang Hu,Cong Chen,Xiaopu Chen,Yagang Feng,Jiang Li
Ytterbium doped lutetium oxide (Yb:Lu 2 O 3 ) transparent ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) of the powders synthesized by the co-precipitation method. The effects of calcination temperature on the composition and morphology of the powders were investigated. Fine and well dispersed 5 at% Yb:Lu 2 O 3 powders with the mean particle size of 67 nm were obtained when calcined at 1100 °C for 4 h. Using the synthesized powders as starting material, we fabricated 5 at% Yb:Lu 2 O 3 ceramics by pre-sintering at different temperatures combined with HIP post-treatment. The influence of pre-sintering temperature on the densities, microstructures and optical quality of the 5 at% Yb:Lu 2 O 3 ceramics was studied. The ceramic sample pre-sintered at 1500 °C for 2 h with HIP post-treating at 1700 °C for 8 h has the highest in-line transmittance of 78.2% at 1100 nm and the average grain size of 2.6 µm. In addition, the absorption and emission cross sections of the 5 at% Yb:Lu 2 O 3 ceramics were also calculated.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2018
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IF 5.091
Yahui Sun,Kaixi Li,Jianghong Zhao,Jianlong Wang,Nan Tang,Dongdong Zhang,Taotao Guan,Zuer Jin
Millimeter-sized nitrogen and sulfur co-doped microporous activated carbon spheres (NSCSs) were first synthesized from poly(styrene-vinylimidazole-divinylbenzene) resin spheres through concentrated H 2 SO 4 sulfonation, carbonization and KOH activation. Styrene (ST) and N-vinylimidazole (VIM) were carbon and nitrogen sources, while the sulfonic acid functional groups introduced by the simple concentrated sulfuric acid sulfonation worked simultaneously as cross-linking agent and sulfur source during the following thermal treatments. It was found that the surface chemistries, textural structures, and CO 2 adsorption performances of the NSCSs were significantly affected by the addition of VIM. The NSCS-4-700 sample with a molar ratio of ST: VIM = 1: 0.75 showed the best CO 2 uptake at different temperatures and pressures. An exhaustive adsorption evaluation indicated that CO 2 sorption at low pressures originated from the synergistic effect of surface chemistry and micropores below 8.04 Å, while at the moderate pressure of 8.0 bar, CO 2 uptake was dominated by the volume of micropores. The thermodynamics suggested the exothermic and orderly nature of the adsorption process , which was dominated by a physisorption mechanism. The high CO 2 adsorption capacity, fast kinetic adsorption rate, and great regeneration stability of the nitrogen and sulfur co-doped activated carbon spheres indicated that the as-prepared carbon adsorbents were good candidates for large-scale CO 2 capture.
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PubMed
高影响因子
Nanomaterials
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2018
·Vol. 8
·期 5
·275
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IF 3.504
Jingting Lu,Chengli Jiao,Zeeshan Majeed,Heqing Jiang
Mesoporous carbons (MC) have attracted a tremendous amount of interest due to their efficient molecular transport properties. However, the limited number of active sites and low microporosity generally impede their use for practical applications. Herein, we have fabricated Mg and N co-doped mesoporous carbon (Mg-NMC) with high microporosity via one-pot synthetic route followed by further steam activation. In comparison with the parent N-doped mesoporous carbon, Mg-NMC shows partially ordered mesostructure and improved CO2adsorption capacity attributed to the introduction of basic site after Mg doping. Upon further steam activation, the microporosity is enhanced to 37.3%, while the CO2adsorption capacity is also increased by 70.4% at 273 K and 1.0 bar.Keywords:mesoporous carbon;Mg doping;steam activation;basic site;microporosity;CO2adsorption
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PubMed
高影响因子
CERAMICS INTERNATIONAL
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2018
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IF 3.057
Yaxiong Du,Hongfei Chen,Guang Yang,Bin Liu,Yanfeng Gao,Hongjie Luo
Titanium carbide based cermets are promising wear resistant coating materials used at elevated temperatures in hostile environment owing to their excellent mechanical, physical and chemical properties. In this work, TiC-Co composite coatings with different Co content, as well as a WC-17Co reference coating are prepared by plasma spraying and their wear resistances are investigated. The friction coefficients and wear rates tested by dry sliding friction at 600 °C are used to characterize the high-temperature wear resistance of the coatings. The phase and microstructure evolution of the coatings before and after friction test are evaluated to conclude the wear mechanisms of these coatings. The results show that as-prepared TiC-Co composite coatings are composed of TiC, Ti, α-Co, r-TiO 2 and CoO phases and Ti oxidizes to r-TiO 2 phase during friction test, which is resulted from decarburization and oxidation of TiC. Among all the coatings, TiC-15Co has the minimum friction coefficient and lowest wear rate. It is contributed to the balanced ratio and good bonding between Co-rich soft phases and Ti-rich hard phases. The wear mechanisms of TiC-Co composite coatings are abrasive wear for low Co content (<15 wt%) coatings and adhesion/fatigue wear for high Co content ones.
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高影响因子
ACS Sustainable Chemistry & Engineering
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2018
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IF 6.14
Han Hu,Ruoyu Zhang,Jinggang Wang,Wu Bin Ying,Jin Zhu
A series of biobased poly(butylene carbonate-co-furandicarboxylate) (PBCF), are synthesized through a two-step polycondensation reaction. Chemical structures, thermal properties, crystallization behaviors, mechanical properties, barrier properties, and enzymatic degradation of PBCFs are investigated. The linear variation of the glass transition temperatures with the content ratio confirms the good miscibility between butylene carbonate (BC) and butylene furandicarboxylate (BF) units. BF segments could crystallize in most contents under different temperatures. Consequently, mechanical properties of these copolymers depend not only on the composition but also on the annealing conditions. Long-time annealing at room temperature or short-time annealing under high temperature could tremendously increase the tensile modulus. For room-temperature annealing, the formation of less perfect crystals of the poly(butylene furandicarboxylate) (PBF) could interpret the enhancement of modulus. On the other hand, the high-temperature annealing induces more perfect PBF crystals and improves the modulus significantly too. The tensile toughness of the PBCFs is good with the lowest elongation at break of 260%, and the degradation could be observed in samples with less than 60 mol % BF units. With good gas barrier properties, fast biodegradability, and high mechanical performance, these copolyesters possess potential applications in the plastic industry.
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2018
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IF 3.141
Hongzhou Xie,Linbo Wu,Bo-Geng Li,Philippe Dubois
Poly(ethylene-co-hexamethylene 2,5-furandicarboxylate) (PEHF) copolyesters with high intrinsic viscosity were synthesized from 2,5-furandicarboxylic acid (FDCA), ethylene glycol (EG), and 1.6-hexanediol (HDO) through two-step melting polycondensation, characterized with 1H NMR, DSC, WAXD, and TGA, and assessed by tensile and impact tests. The molar fraction of HF unit in PEHF (ϕHF), namely, copolymer composition, is higher than the molar fraction of HDO in the feeding diols and can be predicted empirically via Mayer–Lewis equation with apparent reactivity ratio rHDO = 4.6 and rEG = 0.74. All the PEHFs exhibited a single glass transition temperature and excellent thermal stability. HF-rich (ϕHF ≥ 88 mol %) PEHFs are semicrystalline but the others are almost amorphous. In comparison with PEF, PEHFs with ϕHF of 28–36 mol % possess significantly improved tensile ductility (elongation at break 54–160%) and retain high tensile modulus (2.6–2.2 GPa) and yielding strength (71–65 MPa). The tensile properties are comparable to those of bottle-grade PET.
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高影响因子
JOURNAL OF CATALYSIS
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2019
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IF 7.723
Xiaoyong Xu,Lou Pan,Qiutong Han,Chengzhong Wang,Peng Ding,Jing Pan,Jingguo Hu,Haibo Zeng,Yong Zhou
Molybdenum sulfide (MoS 2 ) has attracted considerable attention as one of noble-metal-free co-catalysts of hydrogen evolution reaction (HER) for artificial photosynthetic water splitting. There are well-known challenges in optimizing its catalytic activity to pursue the replacement of platinum (Pt) for HER, owing to the edge-limited active sites and intrinsically poor conductivity. Herein, we prepared metallic MoS 2 nanodots (MNDs) with 1T-phase occupation and edge-exposure maximum to achieve the simultaneous optimization of electric conductivity and active sites. When integrated as co-catalysts with graphitic carbon nitride (g-CN) for sunlight-driven HER in alkaline electrolyte, the outstanding photocatalytic activity with hydrogen evolution rate of 5.62 mmol g −1 h −1 , over 280 times higher than that of pure g-CN, demonstrates the excellent co-catalytic performance of 1T-MoS 2 NDs (1T-MNDs) that even comparable to state-of-the-art Pt. The photo-induced charge dynamics describe the role of 1T-MNDs in facilitating charge separation as well as surface catalytic reaction, suggesting a promising potential of 1T-MNDs with more active sites and higher conductivity as Pt-alternative co-catalysts for solar hydrogen production.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
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2019
·Vol. 35
·期 2
·179-185
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IF 1.071
Jian Juan,Yuan Long,Li He,Liu Huanhuan,Zhang Xinghui,Sun Xuejiao,Yuan Hongming,Feng Shouhua
We used the one-step hydrothermal controlled synthesis method for Co-Ni 3 S 2 ultrathin nanosheets grown directly on nickel foam(NF). The as-synthesized Co-Ni 3 S 2 /NF showed enhanced activities in the hydrogen evolution reaction(HER), oxygen evolution reaction(OER) and better overall water splitting(OWS) efficiency than the un-doped Ni 3 S 2 /NF. The voltage of Co-Ni 3 S 2 /NF for OWS was only 1.58 V at the current density of 10 mA/cm 2 and with long time(>30 h) current output during the current-density( i - t ) test. The good i - t performance was also observed in both HER and OER processes. Additionally, the Co-Ni 3 S 2 /NF showed a large current density(>1 A/cm 2 ) for both HER and OER. When the current densities reached 100 and 1000 mA/cm 2 , the required overpotentials for Co-Ni 3 S 2 /NF were 0.35 and 0.75 V for OER and 0.30 and 0.85 V for HER. Therefore, after introducing Co, th e activity of Ni 3 S 2 -based material was strongly enhanced.
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高影响因子
危险品化学品经营许可证（带存储）