TETRAHEDRON LETTERS
·
2020
·
IF 2.275
Youming Huang,Hongyi Chen,Wenting Zheng,Qingle Zeng
A new protocol for the synthesis of (enantioenriched) benzylic sulfones via the Cu 2 O-catalyzed C–S bond cross coupling of alkane-/arene-sulfinates and (enantioenriched) benzylic quaternary ammonium salts has been developed. The product benzylic sulfones were obtained in good to high yields (75–96%). Chiral arylmethyl sulfones with high enantiomeric excess (90–94% ee) were also synthesized in the presence of Cu 2 O and 1,1′-bis-(diphenylphosphino)ferrocene (dppf).
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Nano Research
·
2020
·Vol. 13
·期 9
·2420-2426
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IF 8.183
Luo Ergui,Wang Chen,Li Yang,Wang Xian,Gong Liyuan,Zhao Tuo,Jin Zhao,Ge Junjie,Liu Changpeng,Xing Wei
Fe/N/C material is the most competitive alternative to precious-metal catalysts for oxygen reduction. In view of the present consensus on active centers, further effort is directed at maximizing the density of single Fe atoms. Here, the imperfections in commonly used doping strategy of Fe for the synthesis of zeolitic imidazolateframework (ZIF)-derived Fe/N/C catalysts are revealed. More importantly, a strikingly improved catalyst is obtained by a ‘second pyrolysis’ method and delivers a half-wave potential of 0.825 V (vs. RHE) in acidic media. The strong confinement effect of carbonaceous host accounts for the formation of dense single-atom sites and thus the high activity. Our findings will potentially facilitate future improvement of M/N/C catalysts.
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Green Energy & Environment
·
2020
·
IF 6.395
Yu Qiu,Li Ma,Qingfeng Kong,Min Li,Dongxu Cui,Shuai Zhang,Dewang Zeng,Rui Xiao
Operating chemical looping process at mid-temperatures (550–750 °C) presents exciting potential for the stable production of hydrogen. However, the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics. Although the reactivity at mid-temperature can be improved by the addition of noble metals, the high cost of these noble metal containing materials significantly hindered their scalable applications. In the current work, we propose to incorporate earth-abundant metals into the iron-based spinel for hydrogen production in a chemical looping scheme at mid-temperatures. Mn 0.2 Co 0.4 Fe 2.4 O 4 shows a high hydrogen production performance at the average rate of ∼0.62 mmol g −1 min −1 and a hydrogen yield of ∼9.29 mmol g −1 with satisfactory stability over 20 cycles at 550 °C. The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam. The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials, enabling their potential for industrial applications.
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ChemElectroChem
·
2020
·Vol. 7
·期 14
·3082-3088
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IF 4.154
Jinzhou Yang,Zong-Bao Yu,Wei Sun,Yue Li,Hongda Wu,Zhongxing Geng,Zhanxu Yang
Graphical One for both : A composite catalyst consisting of WP nanorods, WS 2 , and carbon is presented here. It demonstrates hydrogen evolution reaction (HER) activity and long-term chronopotentiometric stability as well as suitability in both acid electrolyte and alkaline electrolyte. Thorough characterization is performed to uncover the reasons behind uncover the enhanced HER. Through a stepwise synthesis, intercalation followed by chemical vapor deposition (CVD) method, WP nanorods have been grown on the surface of WS 2 /C composite. Compared to WS 2 /C, WP nanorods@WS 2 /C demonstrate better hydrogen evolution reaction (HER) activity and long-term chronopotentiometric stability as well as suitability in both acid electrolyte and alkaline electrolyte. In order to uncover the enhanced HER property reason, systematic characterizations were applied to assist analyzing. The characterizations used include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), electrochemical active surface area (ECSA), Raman, and BET. Based on the analysis, it points that improved ECSA, synergy between WS 2 and WP nanorods, and enhanced degree of graphitization as well, leads to better HER activities of WP nanorods@WS 2 /C over WS 2 /C. This work highlights significant role of WP nanorods in WP/WS 2 /C three-phase composite in electrocatalytic hydrogen evolution and may evoke new interest in related nanostructure study.
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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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INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
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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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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PubMed
高影响因子
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
·
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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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 42
·16546-16554
·
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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Natural Product Communications
·
2020
·
IF 0.468
Qiushan Zhang,Jin Shao,Tong Zhao,Lei He,Huiping Ma,Linlin Jing
In the present study, the antioxidant property of 4 flavones (moslosooflavone, wogonin, isowogonin, and norwogonin) was evaluated using 6 different assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH·), superoxide (O2 •−), and nitric oxide (NO) radical scavenging assays, ferrous iron chelation, reducing power, and total antioxidant capacity. The 4 flavones exhibited antioxidant activities with decreasing order as norwogonin > isowogonin >> wogonin> moslosooflavone. The present results demonstrated that norwogonin and isowogonin exhibited excellent antioxidant activity, which was mainly based on the presence of C-8 hydroxyl group.
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