NEW CARBON MATERIALS
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2015
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IF 0.979
Gang Wang,Li-tao Jia,Bo Hou,De-bao Li,Jun-gang Wang,Yu-han Sun
Fabricating self-supporting, three dimensional graphene macroscopic structures from two dimensional graphene sheets by self-assembly has been an intriguing subject in exploring the performance of graphene structures for practical advanced applications. Monolithic graphene hydrogels (GHs) with quite good mechanical properties and excellent resilience were self-assembled from graphene oxide (GO) dispersions under hydrothermal conditions by changing the pH value. The structure-property relationships and the self-assembly behavior of GHs were investigated. It was found that the formation of GHs was pH-dependent. The charge state of carboxyl groups on the graphene was the key factor that influenced the balance of attraction and repulsion interactions of the GO and consequently determined the self-assembly behavior. Both the graphene molecular structure and colloidal interactions were correlated with the unique self-assembly behavior, which can be used to design graphene arrangements with various structures, functions and mechanical properties. This method is superior to the conventional method that adjusts the concentration and reduction time of the GO dispersion.
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DOI
高影响因子
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
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2016
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IF 1.34
Dong HUANG,Ming-yu ZHANG,Qi-zhong HUANG,Li-ping WANG,Xian TANG,Xin YANG,Kai TONG
A novel SiC–ZrB 2 coating was prepared using a two-step technique by slurry-sintering and chemical vapor reaction on carbon/carbon (C/C) composites. The SiC–ZrB 2 coating was composed of the scattered ZrB 2 phase and the continuous SiC phase. It was observed that a good adhesion was built between the coating and the C/C composites. The SiC–ZrB 2 coating samples exhibited a better ablation resistance in comparison with the uncoated C/C composites. The SiO 2 –ZrO 2 barrier layer, the heat dissipation of the gaseous products and the pinning effect of ZrO 2 all contributed to the good ablation resistance of the SiC–ZrB 2 coated composites.
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DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Zhifeng Dai,Fang Chen,Qi Sun,Yanyan Ji,Liang Wang,Xiangju Meng,Feng-Shou Xiao
An efficient catalyst system based on a Pd-metalated porous organic polymer bearing phenanthroline ligands was designed and synthesized. This catalyst was applied to various C–C bond-forming reactions, including the Suzuki, Heck and Sonogashira couplings, and afforded the corresponding products while exhibiting excellent activities and selectivities. More importantly, this catalyst can be readily recycled. These features show that such catalysts have significant potential applications in the future.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Junjie Zhang,Fang Lu,Weiqiang Yu,Rui Lu,Jie Xu
Lactic acid is produced as a major byproduct during sorbitol hydrogenolysis under alkaline conditions. We investigated the effects of two different alkaline additives, Ca(OH) 2 and La(OH) 3 , on lactic acid formation during sorbitol hydrogenolysis over Ni/C catalyst. In the case of Ca(OH) 2 , the selectivity of lactic acid was 8.9%. In contrast, the inclusion of La(OH) 3 resulted in a sorbitol conversion of 99% with only trace quantities of lactic acid being detected. In addition, the total selectivity towards the C2 and C4 products increased from 20.0% to 24.5% going from Ca(OH) 2 to La(OH) 3 . These results therefore indicated that La(OH) 3 could be used as an efficient alkaline additive to enhance the conversion of sorbitol. Pyruvic aldehyde, which is formed as an intermediate during sorbitol hydrogenolysis, can be converted to both 1,2-propylene glycol and lactic acid by hydrogenation and rearrangement reactions, respectively. Notably, these two reactions are competitive. When Ca(OH) 2 was used as an additive for sorbitol hydrogenolysis, both the hydrogenation and rearrangement reactions occurred. In contrast, the use of La(OH) 3 favored the hydrogenation reaction, with only trace quantities of lactic acid being formed.
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高影响因子
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
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2014
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IF 2.613
Yoshiaki Oda,Heping Shen,Lin Zhao,Jianbao Li,Mitsumasa Iwamoto,Hong Lin
An environmentally friendly solid-state quantum dot sensitized solar cell (ss-QDSSC) was prepared by combining colloidal SnS QDs as the sensitizer and organic hole scavenger spiro-OMeTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)9,9′-spirobifluorene) as the solid-state electrolyte, and the energy alignment of SnS and TiO2 was investigated. The bandgap of colloidal SnS QDs increased with decreasing particle size from 14 to 4 nm due to an upshift of the conduction band and a downshift of the valence band. In TiO2/SnS heterojunctions, the conduction band minimum (CBM) difference between TiO2 and SnS was as large as ∼0.8 eV; this difference decreased with decreasing particle size, but was sufficient for electron injection from SnS nanoparticles of any size into TiO2. Meanwhile, the sensitizer regeneration driving force, that is, the difference between the valence band maximum (VBM) of SnS and the work function of the electrolyte, showed an opposite behaviour with the SnS size due to a downward shift of the SnS VB. Consequently, smaller SnS QDs should result in a more efficient charge transfer in heterojunctions, revealing the advantages of QDs vs larger particles as sensitizers. This prediction was confirmed by the improved photovoltaic performance of ss-QDSSCs modified with SnS nanoparticles, which peaked for 5–6 nm sized SnS nanoparticles due to the balance between electron injection and sunlight absorption.
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DOI
PubMed
高影响因子
Journal of Integrative Agriculture
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2016
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IF 0.724
Bo CHENG,Hai-feng LIAN,Ying-ying LIU,Xin-hui YU,Ya-li SUN,Xiu-dong SUN,Qing-hua SHI,Shi-qi LIU
A hydroponic study was conducted to determine the effects of selenium (Se: 0, 3, 6 μmol L –1 ) on senescence-related oxidative stress in garlic plants grown under two sulfur (S) levels. We evaluated the yields of plants harvested at 160 and 200 days after sowing. Plants grown under a low Se dose (0.3 μmol L –1 ) at low S level showed higher yields (12.0% increase in fresh weight yield, 13.7% increase in dry weight yield) than the controls, despite a decrease in chlorophyll concentration. Compared with control plants, the Se-treated plants showed lower levels of lipid peroxidation. The Se-treated plants also showed higher activities of glutathione peroxidase and catalase, but lower superoxide dismutase activities. Changes in F v / F m values and proline contents were affected more strongly by S than by Se. On the basis of our results, we can conclude that Se plays a key role in the antioxidant systems in garlic seedlings. It delays senescence by alleviating the peroxide stress, but it can be toxic at high levels. A high S level may increase tolerance to high Se concentrations through reducing Se accumulation in plants.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Xiao Deng,Shilin Cao,Ning Li,Hong Wu,Thomas J. Smith,Minhua Zong,Wenyong Lou
A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles (PD-MNPs) was prepared and characterized. The widely used Aspergillus niger lipase (ANL) was immobilized on the PD-MNPs (ANL@PD-MNPs) with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significantly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy. A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin (DMY) in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Jianqiang Zhang,Yongsheng Peng,Wenguang Leng,Yanan Gao,Feifei Xu,Jinling Chai
We introduced bipyridine ligands into a series of two-dimensional (2D) covalent organic frameworks (COFs) using 2,2′-bipyridine-5,5′-dicarbaldehyde (2,2′-BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2′-BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyridine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be varied, with one ligand favoring binding in the space between adjacent COFs′ layers and the other ligand favoring binding within the pores of the COFs. The Pd(II)-loaded COFs exhibited good catalytic activity for the Heck reaction.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Yanke Yu,Jinsheng Chen,Jinxiu Wang,Yanting Chen
A series of CuSO 4 /TiO 2 catalysts were prepared using a wet impregnation method. The activity of each sample in the selective catalytic reduction of NO by NH 3 (NH 3 -SCR) was determined. The effects of SO 2 and H 2 O, and their combined effect, on the activity were examined at 340 °C for 24 h. The catalysts were characterized using N 2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction of H 2 (H 2 -TPR), temperature-programmed desorption of NH 3 (NH 3 -TPD), and in situ diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS). The CuSO 4 /TiO 2 catalysts had good activities, with low production of N 2 O above 340 °C. SO 2 or a combination of SO 2 and H 2 O had little effect on the activity, and H 2 O caused only a slight decrease in activity during the experimental period. The NH 3 -TPD and H 2 -TPR results showed that CuSO 4 increased the amounts of acid sites and adsorbed oxygen on the catalyst. In situ DRIFTS showed that the NH 3 -SCR reaction on the CuSO 4 /TiO 2 catalysts followed an Eley–Rideal mechanism. The reaction of gaseous NO with NH 3 adsorbed on Lewis acid sites to form N 2 and H 2 O could be the main reaction pathway, and oxygen adsorption might favor this process.
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高影响因子
NEW CARBON MATERIALS
·
2016
·
IF 0.993
Yue Wang,Wen-ting Wu,Ming-bo Wu,Hong-di Sun,Hui Xie,Chao Hu,Xue-yan Wu,Jie-shan Qiu
Yellow-visual fluorescent carbon quantum dots (CQDs) were prepared from petroleum coke by ultrasonic-assisted chemical oxidation and were used as label-free probes for Cu 2+ detection in water. The detection of Cu 2+ by CQD probes is related to a quenching of fluorescence by a photoinduced electron transfer mechanism. The quenched fluorescence of the CQDs by Cu 2+ can be recovered by adding ethylene diamine tetraacetic acid. The yellow-visual fluorescent CQD probes have a linear detection range from 0.25 to 10 μM, a detection limit of 0.0295 μM, a response time of 3 s, and a superior sensitivity and selectivity for Cu 2+ detection compared to other fluorescent probes. The CQDs are easy to prepare, economical, reusable, fast to respond and can be used in on-line detection.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Na Li,Dan Xu,Di Bao,Jinling Ma,Xinbo Zhang
Rechargeable Na-O 2 batteries have attracted significant attention as energy storage devices owing to their theoretically high energy storage capacity and the natural abundance of sodium. However, practical applications of this type of battery still suffer from low specific capability, poor cycle stability, instable electrolytes, and unstable polymer binders. Herein, we report a facile method of synthesizing binder free and flexible cathodes with Co 3 O 4 nanowire arrays vertically grown onto carbon textiles. When employed as a cathode for Na-O 2 batteries, this cathode exhibits superior performance, including a reduction of charge overpotential, high specific capacity (4687 mAh/g), and cycle stability up to 62 cycles. These enhanced performance can be attributed to the synergistic effect of the porosity and catalytic activity of the Co 3 O 4 nanowire catalyst.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
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IF 2.628
Yangzhi Bai,Baolian Yi,Jia Li,Shangfeng Jiang,Hongjie Zhang,Zhigang Shao,Yujiang Song
The development of a non-precious metal electrocatalyst (NPME) with a performance superior to commercial Pt/C for the oxygen reduction reaction (ORR) is important for the commercialization of fuel cells. We report the synthesis of a NPME by heat-treating Co-based metal organic frameworks (ZIF-67) with a small average size of 44 nm. The electrocatalyst pyrolyzed at 600 °C showed the best performance and the performance was enhanced when it was supported on BP 2000. The resulting electrocatalyst was composed of 10 nm Co nanoparticles coated by 3–12 layers of N doped graphite layers which as a whole was embedded in a carbon matrix. The ORR performance of the electrocatalyst was tested by rotating disk electrode tests in O 2 -saturated 0.1 mol/L KOH under ambient conditions. The electrocatalyst (1.0 mg/cm 2 ) showed an onset potential of 1.017 V (vs. RHE) and a half-wave potential of 0.857 V (vs. RHE), which showed it was as good as the commercial Pt/C (20 μg Pt /cm 2 ). Furthermore, the electrocatalyst possessed much better stability and resistance to methanol crossover than Pt/C.
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高影响因子
危险品化学品经营许可证（带存储）