Journal of the American Chemical Society
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2015
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IF 12.113
Haiyan Jin,Jing Wang,Diefeng Su,Zhongzhe Wei,Zhenfeng Pang,Yong Wang
Remarkable hydrogen evolution reaction (HER) or superior oxygen evolution reaction (OER) catalyst has been applied in water splitting, however, utilizing a bifunctional catalyst for simultaneously generating H2 and O2 is still a challenging issue, which is crucial for improving the overall efficiency of water electrolysis. Herein, inspired by the superiority of carbon conductivity, the propitious H atom binding energy of metallic cobalt, and better OER activity of cobalt oxide, we synthesized cobalt–cobalt oxide/N-doped carbon hybrids (CoOx@CN) composed of Co0, CoO, Co3O4 applied to HER and OER by simple one-pot thermal treatment method. CoOx@CN exhibited a small onset potential of 85 mV, low charge-transfer resistance (41 Ω), and considerable stability for HER. Electrocatalytic experiments further indicated the better performance of CoOx@CN for HER can be attributed to the high conductivity of carbon, the synergistic effect of metallic cobalt and cobalt oxide, the stability of carbon-encapsulated Co nanoparticles, and the introduction of electron-rich nitrogen. In addition, when used as catalysts of OER, the CoOx@CN hybrids required 0.26 V overpotential for a current density of 10 mA cm–2, which is comparable even superior to many other non-noble metal catalysts. More importantly, an alkaline electrolyzer that approached ∼20 mA cm–2 at a voltage of 1.55 V was fabricated by applying CoOx@CN as cathode and anode electrocatalyst, which opened new possibilities for exploring overall water splitting catalysts.
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PubMed
高影响因子
VACUUM
·
2015
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IF 1.858
Zhaobing Cai,Guo Jin,Xiufang Cui,Yang Li,Yang Fan,Jiahui Song
In this work, a NiCrCoTiV HEA was fabricated by vacuum hot-pressing sintering after planetary ball milling. The microstructure and phase composition were studied by experiment and thermodynamic simulation. The results show that some discrepancies are found between the calculated and experimental results, and the main difference is the existence of TiO phase. Experimental results indicate that, the alloy consists of a BCC phase, an FCC phase, an eta (η) phase, a TiO phase and Ni 2 V 3 intermetallic compounds , and BCC phase is enriched with Cr and V elements, FCC phase is enriched with Co, Ti and Ni and heavily depleted by V and Cr, and eta phase is enriched with Ni, Ti, and Co elements. The thermodynamic simulation results suggest that the solidification simulation predicts the composition of BCC phase, FCC phase and eta (η) phase very well, but can't predict the presence of Ni 2 V 3 intermetallic compounds. Without regard to the composition of each phase, the results of the simulated equilibrium phase diagram seem to be much closer to the experimental results.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2014
·Vol. 30
·期 3
·362-367
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IF 1.119
Cao Li,Jia Chunman,Zhang Qi,Chen Da,Zhang Chunyan,Qian Yaao
A fluorescent probe with a coumarin moiety bound to rhodamine 6G hydrazide( 1 ) was synthesized. Its sensing behavior toward various metal ions was investigated with fluorescence methods. Compound 1 displays different fluorescence emission responses to Al 3+ and Ca 2+ at the same excitation wavelength in the visible light region, while no changes occur after the addition of other metal ions. The binding ratios of the complexs of 1 -Al 3+ and 1 -Ca 2+ are both 2:1 according to the Job plot and high resolution mass spectrometer(HRMS) experiments. Moreover, emission spectrum of 1 -Ca 2+ complex and absorption spectrum of the rhodamine dyes overlap largely. When Al 3+ was added to the 1 -Ca 2+ system, calcium in complex 1 -Ca 2+ can be displaced by Al 3+ , resulting in the output of another ratiometric sensing signal, which demonstrates that the 1 -Ca 2+ complex can be served as a new and effective fluorescence resonance energy transfer(FRET) donor for rhodamine derivatives.
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International Journal of Nanomedicine
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2017
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IF 4.3
Quan-Quan Zhuang,Zhi-Hang Lin,Yan-Cheng Jiang,Hao-Hua Deng,Shao-Bin He,Li-Ting Su,Xiao-Qiong Shi,Wei Chen
Dendrite-like cobalt selenide nanostructures were synthesized from cobalt and selenium powder precursors by a solvothermal method in anhydrous ethylenediamine. The as-prepared nanocrystalline cobalt selenide was found to possess peroxidase-like activity that could catalyze the reaction of peroxidase substrates in the presence of H2O2. A spectrophotometric method for uric acid (UA) determination was developed based on the nanocrystalline cobalt selenide-catalyzed coupling reaction between N-ethyl-N-(3-sulfopropyl)-3-methylaniline sodium salt and 4-aminoantipyrine (4-AAP) in the presence of H2O2. Under optimum conditions, the absorbance was proportional to the concentration of UA over the range of 2.0–40 μM with a detection limit of 0.5 μM. The applicability of the proposed method has been validated by determination of UA in human serum samples with satisfactory results.
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PubMed
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JOURNAL OF ASIA-PACIFIC ENTOMOLOGY
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2017
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IF 1.046
Yunhua Zhang,Jinyun Ji,Xiao Zhao,Ruoheng Jin,Jianhong Li,Hu Wan
A previous study demonstrated that a β- N -acetyl- d -hexosaminidase ( NlHex4 ) from the brown planthopper could serve as a new potential target for biopesticides due to its requirement for molting, and lethal phenotypes were observed via RNA interference . However, the enzymatic properties of NlHex4 remain unclear. In the present study, NlHex4 was expressed, purified and characterized. Recombinant NlHex4 was functionally expressed in baculovirus-infected insect cells and purified with a molecular weight of approximately 70 kDa. Recombinant NlHex4 had an optimal pH and temperature of 6.0 and 60 °C, respectively. Moreover, recombinant NlHex4 exhibited thermal stability at 50 °C for at least 1 h. Furthermore, the activity of recombinant NlHex4 was inhibited by the metal ions Fe 2 + and Fe 3 + and the serine protease inhibitor phenylmethanesulfonyl fluoride. These results reveal the enzymatic properties of NlHex4 and provide a basis for future investigation of the interaction between HEX and chitin oligosaccharide .
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Catalysis Science & Technology
·
2016
·Vol. 6
·期 12
·4503-4510
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IF 5.287
Diefeng Su,Zhongzhe Wei,Shanjun Mao,Jing Wang,Yi Li,Haoran Li,Zhirong Chen,Yong Wang
Efficient and inexpensive catalysts are urgently desired for the hydrogenation of 2,3,5-trimethylbenzoquinone (TMBQ) to 2,3,5-trimethylhydroquinone (TMHQ), a key vitamin-E intermediate. In this study, a one-step method was developed to synthesize uniform cobalt-based NPs supported on porous nitrogen-doped carbon for the hydrogenation of TMBQ to TMHQ. The as-prepared catalyst shows a high yield (>90%) and selectivity (>99%) for TMBQ hydrogenation as well as α,β-unsaturated carbonyls. The satisfactory performance is attributed to the small particle size and homogeneous distribution. Meanwhile, metallic Co is proved to be responsible for the catalytic activity. Furthermore, density functional theory calculation discloses that the excellent chemoselectivity towards TMBQ is due to the preference for a desorption process over sequential hydrogenation of TMHQ. This novel material has great potential as a non-precious-metal catalyst for heterogeneous hydrogenation processes, due to its outstanding catalytic performance, simple preparation method and low production cost.
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MATERIALS & DESIGN
·
2016
·
IF 3.997
Xinjian Cheng,Yun Yu,Yiru Jia,Lian Duan
Three small molecular boron dipyrromethene (BODIPY) derivatives (B3a, B3b and B3c) were well-designed and synthesized at first, and then were incorporated into polyurethane to obtain macromolecular fluorescent sensors. These small molecular BODIPY derivatives exhibited high sensitivity and selectivity to Hg 2 + , Cr 3 + and Fe 3 + ions. The colors of these chemicals changed rapidly upon the addition of Hg 2 + , Cr 3 + and Fe 3 + ions. In addition, their fluorescence peaks shifted and was enhanced as well. B3a, B3b and B3c still remained the sensing properties when being introduced to polyurethane (PU). The functionalized PU films not only showed color change and fluorescence shift for detecting Hg 2 + , Cr 3 + and Fe 3 + ions as their small molecular counterparts, but also triggered a new emission peak in 500–600 nm. Besides, the functionalized PU film (PU-B3a as a sample) could absorb Hg 2 + ions more than 84 mg/g in unit time and volume. It suggested that as long as the structure of the small molecular sensor was remained, the fluorescent ability remained even it is introduced to the macromolecular chains. In addition, Glass transition temperature (T g ) of the PU films changed when B3a, B3b and B3c were introduced.
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MATERIALS CHEMISTRY AND PHYSICS
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2017
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IF 2.084
Yiru Jia,Yi Pan,Haiying Wang,Rong Chen,Hua Wang,Xinjian Cheng
A fluorescent monomer of boron dipyrromethene (BODIPY) derivative ( 9AnPD) is designed and synthesized at first, and then it is introduced into polyurethane to obtain polymeric chemosensor with dangling fluorescent side groups. The monomer chemosensor 9AnPD exhibits highly selective properties to Hg 2+ ion in a wide pH range. The color of the monomer changed rapidly upon the addition of Hg 2+ ion. The fluorescence peak shifted and is enhanced about 4-flod. In addition, the monomer chemosensor reaches the detection limit of Hg 2+ is as low as 5 × 10 −6 m. When the fluorescent monomer is introduced to polymers, the sensing properties of the monomer chemosensor 9AnPD still remained. The polymer chemosensors not only exhibit fluorescence shift and color change for identifying Hg 2+ ion as its monomer chemosensor, but also improve the efficiency of detection. The detection limit of polymer chemosensor could reach 5 × 10 −7 m , and the fluorescence enhanced about 6-flod. The glass transition temperature (T g ) of the fluorescent PU is increased with the introduction of 9AnPD . However, it is about 60 °C, and will not lead to any adverse effect for the process. The molecular weights of PUs are lower than which without 9AnPD , but still of the macromolecular level.
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MATERIALS CHARACTERIZATION
·
2016
·
IF 2.383
Zhaobing Cai,Guo Jin,Xiufang Cui,Zhe Liu,Wei Zheng,Yang Li,Liquan Wang
Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti 2 compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH mix , ΔS mix and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially when Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti 2 compound phases.
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MATERIALS SCIENCE FORUM
·
2017
·
IF 0
Zhao Bing Cai,Xue Jia Pang,Xiu Fang Cui,Xin Wen,Zhe Liu,Mei Ling Dong,Yang Li,Guo Jin
In order to improve the surface properties of Ti-6Al-4V, high-entropy alloy coatings were prepared by in-situ laser cladding on the surface of Ti-6Al-4V substrate. The microstructure, micro-hardness, corrosion resistance and wear resistance were investigated. The results showed that the high-entropy alloy coating was composed of BCC high-entropy alloy phase, α-Ti phase and (Ni, Co)Ti2 phase. The micro-hardness of the high-entropy alloy coatings is much higher than that of Ti-6Al-4V substrate. The coating also has a better corrosion resistance than Ti-6Al-4V substrate, even superior to 304SS in 3.5wt.% NaCl solution at room temperature. Compared with Ti-6Al-4V substrate, the high-entropy alloy coating has a greater wear resistance with the wear mass loss decreased 28.2% and 23.1%, respectively. Wear patterns of Ti-6Al-4V substrate and high-entropy alloy coatings are the coexistence of adhesive wear and abrasive wear, but the wear degree of high-entropy alloy coatings is lower.
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ACS Catalysis
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2016
·
IF 9.307
Zhongzhe Wei,Yiqing Chen,Jing Wang,Diefeng Su,Minghui Tang,Shanjun Mao,Yong Wang
Porous nitrogen-doped graphene layers encapsulating cobalt nanoparticles (NPs) were prepared by the direct pyrolysis process. The resulting hybrids catalyze the hydrogenation of diverse quinoline compounds to access the corresponding tetrahydro derivatives (THQs), important molecules present in fine and bulk chemicals. Near-quantitative yields of the corresponding THQs were obtained under optimized conditions. Notably, various useful substituted quinolines and other biologically important N-heteroarenes are also viable. The enhanced stability of the catalyst is ascribed to the encapsulation structure, which can enormously reduce the extent of leaching of base metals and protect metal NPs from growing larger. The achieved success in the encapsulation of metal NPs within graphene layers opens an avenue for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2017
·
IF 3.133
Hai-Bo Zhao,Jin-Bo Cheng,Yu-Zhong Wang
A novel Co@crystalline carbon@carbon aerogel composite with yolk-shell structure was fabricated via a green and facile method using biomass-based alginate aerogels as precursor. In the resultant composite, a large amount of highly crystallized Co nanoparticles (∼41.5 wt%) with a diameter of 5–20 nm was coated with crystalline carbon layer and evenly embedded in the porous carbon aerogel matrix. Due to core-shell Co@crystalline carbon structure, the thermal oxidation stability of the composite can be significantly improved. The porous composite also had the high surface area (425 cm 3 g −1 ) and showed considerable magnetization. Benefitting from the well-designed constitution and structure, the Co@crystalline carbon@carbon aerogel composite showed great microwave absorption performances. When the filler loading of the composite in wax was only 10 wt% and the thickness of the absorber was as thin as 1.5 mm, the maximum RL reached −43 dB. The excellent microwave absorption performances with low filler loading and ultrathin thickness make the aerogel composite show great potential application in the microwave absorption field.
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