Materials
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2019
·Vol. 12
·期 17
·2813
·
IF 2.972
Haijuan Li,Ling Li,Shuaizhi Zheng,Xinming Wang,Zengsheng Ma
To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2(5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2(5%) composite separator has a superior ionic conductivity of 1.26 × 10−3S cm−1and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g−1at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2composite separator exhibits excellent electrochemical performance under high and room temperature environments.Keywords:TiO2nanofiber;PVDF-HFP;composite separator;phase inversion;thermal shrinkage;ionic conductivity
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高影响因子
NEW JOURNAL OF CHEMISTRY
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2019
·Vol. 43
·期 42
·16546-16554
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IF 3.069
Chang Liu,Jing Qiao,Xue Zhang,Dongmei Xu,Nannan Wu,Longfei Lv,Wei Liu,Jiurong Liu
In this paper, we report the facile synthesis of CoNi/C nanocomposites derived from bimetallic metal organic frameworks for electromagnetic wave absorption applications. The effects of carbonation temperature on the phase structure, morphology and microwave absorption properties of the derived nanocomposites were thoroughly studied. Micro-structure characterization results indicated that the obtained CoNi/C composites are composed of numerous fine particles with the size of 20 nm, and in the composites, Ni, Co, and C elements are uniformly distributed. Electromagnetic wave absorption property evaluation showed that CoNi/C obtained at 650 °C outperformed those samples prepared at 500, 800 or 950 °C. The minimum reflection loss (RL) of −74.7 dB could be achieved with a thickness of 1.8 mm at 15.6 GHz. The effective absorption bandwidth (RL ≤ −10 dB) ranged from 2.9 GHz to 18 GHz. This study shows that these porous Co–Ni/C nanocomposites derived from MOFs are attractive candidates as electromagnetic (EM) wave absorbers due to the combined advantages of excellent impedance matching and strong interfacial loss between metallic NPs and porous carbon composites.
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ACS Omega
·
2019
·
IF 2.584
Shuaishuai Ma,Jiandong Gu,Yingxia Han,Yuan Gao,Yuqing Zong,Zhaolian Ye,Jinjuan Xue
Visible-lightdriven C–TiO2 nanocomposites were prepared via a simple calcination and acid etching process. The C–TiO2 nanocomposites were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and high-resolution TEM. The results showed that TiO2 nanoparticles were combined with a porous carbon layer through surface C–O groups, which facilitates the strong interface interaction. The interface combination of nano-TiO2 and carbon material increases the specific surface area of nano-TiO2, widens the range of light response, and improves the efficiency of light-induced electron migration. The visible-light photocatalytic activity of the prepared photocatalyst was evaluated by the decomposition of tetracycline aqueous solution. Compared with that of pure TiO2, the photocatalytic activity of C–TiO2 nanocomposites was significantly improved. Furthermore, a possible photocatalytic mechanism was also tentatively proposed. This work can promote the development of active photocatalysts under solar light for the photodegradation of environmental pollutants.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2019
·
IF 6.393
Jinhong Ye,Dongmei Deng,Yanqin Wang,Liqiang Luo,Kunpeng Qian,Shaomei Cao,Xin Feng
Unique and well-aligned Cu@C core-shell nanocubes were rationally designed for nonenzymatic glucose detection using cubic Cu 2 O nanoparticles immerged in water-soluble polyvinyl pyrrolidone (PVP) coatings as precursor. As a consequence, the optimum Cu@C nanocubes with a shell thickness of ∼6.48 nm were prepared by the initial coating of Cu 2 O nanoparticles with 1.5 mg/mL PVP and subsequent annealing at 600 °C. After thermal annealing process, Cu 2 O nanoparticles were reduced to Cu nanocubes; at the same time, PVP was pyrolyzed to carbon shell encapulating the cubic Cu core. Due to efficient protection of the carbon shell of Cu core from oxidization and the advantageous inter-connected core-shell conductive networks, the hierarchical Cu@C nanocubes exhibit excellent electrocatalytic activity towards glucose oxidation. Under optimum condition, the resulted 600 °C annealed 1.5 mg/mL-Cu@C/Nafion modified glassy carbon electrode displayed high efficient nonenzymatic glucose detection, offering a wide linear range of 40 μM – 40 mM, with low detection limit at 21.35 μM (S/N = 3) and high sensitivity peak of 2565 μA mM –1 cm –2 . More importantly, the well-designed Cu@C core-shell nanocubes could be utilized as a promising nonenzymatic sensor in practical biological applications for the detection of glucose concentration in human serum samples.
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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 44
·期 2
·478-486
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IF 3.069
Feng Li,Shanshan Jiang,Jin Huang,Yue Wang,Shiyu Lu,Cuiqin Li
Carbon-encapsulated Fe3O4 (Fe3O4@C) catalysts were prepared by a solvothermal method using glucose as the carbon source and their physicochemical properties were characterized via various analytical techniques. Catalytic transfer hydrogenation of furfural over Fe3O4@C catalysts was investigated with isopropanol as the solvent and hydrogen donor. The Fe3O4@C catalysts exhibited high catalytic furfural transfer hydrogenation activity, selectivity of furfuryl alcohol, and high reusability. The mechanism of catalytic transfer hydrogenation of furfural by Fe3O4@C obeys the Meerwein–Ponndorf–Verley reduction on a Lewis acid site (Fe3O4).
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Ling Zhang,Xijian Liu,Min Zhang,Haikuan Yuan,Lijuan Zhang,Jie Lu
We present here a novel, simple, low cost and green synthetic strategy for unique core-shell structured Fe 3 O 4 @C-MoO 2 -Ni composites without using extra reducing agent. The Fe 3 O 4 @C-MoO 2 -Ni composites exhibited better catalytic performance (reduction of 4-nitrophenol to 4-aminophenol) than previous common catalysts because highly dense satellite Ni nanoparticles firmly distributed on the porous carbon spheres. In addition, the Fe 3 O 4 @C-MoO 2 -Ni composites can be used as a pollutant remover due to fast adsorption rate and high adsorption capacity for dye in water. More importantly, owing to high magnetic susceptibility , the Fe 3 O 4 @C-MoO 2 -Ni composites show excellent performance for recyclable use by magnetic separation. Thus, the Fe 3 O 4 @C-MoO 2 -Ni composites have great potential as an ideal catalyst and adsorbent due to facile and green synthesis method, good stability, excellent recyclability, nontoxic and low cost properties.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
·
IF 4.175
Xianfeng Meng,Shenhui Dong
C/Co composites are promising materials for electromagnetic (EM) wave absorption. In this work, C/Co nanofibres were synthesised via a facile electrospinning method followed by an in situ reduction process. The results indicate that the heterogeneous structure and Co content play a vital role in determining the EM wave absorption performance of the C/Co nanofibres. At 15 wt% Co content, the C/Co nanofibres exhibit optimal impedance matching and attenuation ability, and the minimum reflection loss for the sample with thickness 3.5 mm is −58.8 dB. The effective absorption bandwidth reaches 12.9 GHz in the range of 2–18 GHz, which partially and completely covers the C and X-Ku bands, respectively. The EM wave absorption mechanism based on the conductive, dielectric , and magnetic losses is discussed in detail. The results indicate that the C/Co nanofibres possess significant potential for microwave absorption applications.
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CHEMICAL GEOLOGY
·
2019
·
IF 3.618
Ying Wang,Xiu Yuan,Xiaomin Li,Fangbai Li,Tongxu Liu
Cytochrome c ( c -Cyts), as a key protein involved in extracellular electron transfer , plays an important role in the microbial Fe(II)-oxidizing process. In this study, due to their similar structure with the outer membrane protein of microorganisms , the equine c -Cyts was employed as a model protein to examine the impact of different organic ligands on the redox kinetics between Fe(II) and c -Cyts using the rapid stopped-flow spectrometer. Our results suggest that the presence of organic ligands will significantly accelerate the reaction between c -Cyts and Fe(II), with reaction rates obtained in the following order: EDTA > citric acid (Cit) > NTA > malonic acid (Mal) > glycine amino acid (Gly) > acetate acid (Ace) > control. It was also found from the kinetic modeling results that the reduction rate of c -Cyts by Fe(II)-ligands was closely correlated to the complex constant between Fe(II) and each ligand, and the reduction rate constants of c -Cyts by Fe(II)L species (L represents “ligands”). Further analysis on the ligand structure indicates that the reaction rate constants are highly correlated with the complex constants of Fe(II)-ligand and the reduction rate constants of c -Cyts by Fe(II)L species ( k 3 ) for Group I (Gly, NTA, and EDTA) and Group II (Cit, Mal, and Ace). The results of midpoint potentials of all Fe(II)-ligands obtained through cyclic voltammetry (CV) experiments were ranked as Ace < Gly < NTA < control < Mal < EDTA < Cit, indicating that the redox potentials of Fe(II) complexes in the same group with similar structures were positively correlated with Fe(II)-ligand complex constants. The reorganization energy change of the electron-transfer reaction resulting from the different Fe(II)-ligand structures may contribute significantly more than does the Gibbs free energy (Δ G ) to the reaction kinetics of Fe(II)-ligand and c -Cyts.
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INTERNATIONAL JOURNAL OF ENERGY RESEARCH
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2019
·Vol. 44
·期 2
·977-987
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IF 3.343
Chuan Ding,Weilong Xu,Min Wang,Xueqin Zeng,Wei Wang
Summary ZnCo 2 O 4 /C microhydrangeas with controllable microstructure are successfully synthesized through a simple citrate-guided solvothermal method and following thermal decomposition. The experimental results reveal that the citrate-directed self-regulation of Zn-Co-EG agglomerates play a critical role in the formation of the hydrangea-like precursors. When applied as anode material in lithium ion batteries (LIBs), ZnCo 2 O 4 /C microhydrangeas exhibited high available capacities of 964.6 mAh g −1 at 1 A g −1 after 200 cycles and 704.4 mAh g −1 at 4 A g −1 over 1000 cycles. The excellent reliability is attributed to the superior microstructure that provides many benefits including enhanced electron or ion transport and improved structure stability, etc.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 31
·期 1
·226-238
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IF 2.195
Shen Yongqian,Wei Yupeng,Li Jian,Zhang Yuchen,Li Bin,Lu Xuefeng,Ji Binghan,Yan Pengze,Du Xueyan
Electromagnetic (EM) wave absorbing materials with superhydrophobic property and enhanced microwave absorbing ability are very important for the application of stealth technologies, especially in humid conditions. In the present work, the electrospinning technique was employed to fabricate NiAc/PVA nanofibers (NFs) from nickel acetate tetrahydrate (NiAc) and poly(vinyl alcohol) (PVA) solution as precursors, while the PVA component was further pyrolyzed and carbonized to obtain Ni/NiO/C NFs. Microwave absorption performance and EM parameters of the prepared NFs were then investigated from 2.0 to 18.0 GHz. Comparative studies between different samples elucidated not only the possible causes for lose mechanisms, but also impedance matching. According to the experimental results, when NiAc/PVA NFs contained 8% NiAc, the calcinated Ni/NiO/C NFs could achieve an optimum reflection loss of − 33.9 dB at 10.4 GHz under a thickness of 2.5 mm and exhibit an effective frequency bandwidth of 5.7 GHz. Furthermore, the membrane of Ni/NiO/C NFs with the best absorption property exhibited robust hydrophobicity and the contact angle was 144.9°, It shows that the obtained Ni/NiO/C NFs have a broad application prospect in waterproof stealth materials.
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ACS Omega
·
2019
·
IF 2.584
Yuxiang Wu,Yan Huang,Hong Huang,Yaseen Muhammad,Zuqiang Huang,Joseph Winarta,Yanjuan Zhang,Shuangxi Nie,Zhongxing Zhao,Bin Mu
Silkworm excrement is a very useful biomass waste, composed of layer-structured fats and proteins, which are great precursors for carbon composite materials. In this work, new porous composites derived from silkworm excrement were prepared for selective separation of flavor 4-methylanisole from the binary 4-methylanisole/4-anisaldehyde mixture. In particular, the silkworm excrement, possessing a unique nanosheet structure, is converted into a graphite-like carbon by a simple calcination strategy followed by a metal-ion-doping procedure. This Fe@C composite exhibits a special nano-spongy morphology, anchoring Fe3C/Fe5C2 on the carbon nanosheets. Density functional theory simulations showed that 4-methylanisole presents a stronger π–π interaction and attraction forces with sp2 carbon nanosheets in Fe@C composites than 4-anisaldehyde. The selective adsorption experiments further confirmed that the Fe@C composites exhibited a 4-methylanisole capacity of 7.3 mmol/g at 298 K and the highest selectivity of 17 for an equimolar 4-methylanisole/4-anisaldehyde mixture among the examined adsorbents including MOFs and commercial activated carbon materials, which demonstrates the potential of this low-cost and eco-friendly porous carbon material as a promising sustainable adsorbent.
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高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2019
·Vol. 29
·期 33
·1902875
·
IF 15.621
Zhichao Wang,Wenjia Xu,Xiaokang Chen,Yanhua Peng,Yanyan Song,Chunxiao Lv,Hongli Liu,Junwei Sun,Ding Yuan,Xiyan Li,Xiangxin Guo,Dongjiang Yang,Lixue Zhang
Heteroatom doping plays a significant role in optimizing the catalytic performance of electrocatalysts. However, research on heteroatom doped electrocatalysts with abundant defects and well-defined morphology remain a great challenge. Herein, a class of defect-engineered nitrogen-doped Co 3 O 4 nanoparticles/nitrogen-doped carbon framework (N-Co 3 O 4 @NC) strongly coupled porous nanocubes, made using a zeolitic imidazolate framework-67 via a controllable N-doping strategy, is demonstrated for achieving remarkable oxygen evolution reaction (OER) catalysis. X-ray photoelectron spectroscopy, X-ray absorption fine structure, and electron spin resonance results clearly reveal the formation of a considerable amount of nitrogen dopants and oxygen vacancies in N-Co 3 O 4 @NC. The defect engineering of N-Co 3 O 4 @NC makes it exhibit an overpotential of only 266 mV to reach 10 mA cm −2 , a low Tafel slope of 54.9 mV dec −1 and superior catalytic stability for OER, which is comparable to that of commercial RuO 2 . Density functional theory calculations indicate N-doping could promote catalytic activity via improving electronic conductivity, accelerating reaction kinetics, and optimizing the adsorption energy for intermediates of OER. Interestingly, N-Co 3 O 4 @NC also shows a superior oxygen reduction reaction activity, making it a bifunctional electrocatalyst for zinc–air batteries. The zinc–air battery with the N-Co 3 O 4 @NC cathode demonstrates superior efficiency and durability, showing the feasibility of N-Co 3 O 4 /NC in electrochemical energy devices.
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