APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Qijie Mo,Wenbiao Zhang,Liuqing He,Xiang Yu,Qingsheng Gao
Exploring noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is the key issue in hydrogen economy blueprint. Herein, bimetallic Ni 2-x Co x P supported by N-doped carbon nanofibers (denoted as Ni 2-x Co x P/N-C NFs) are developed via electrospinning followed by pyrolysis under an inert flow. The space confinement by in-situ formed N-doped carbon matrix produces ultrafine Ni 2-x Co x P with abundant active-sites. More importantly, the engineering on Ni 2-x Co x P solid-solution-alloys can vary electronic configuration and consequently optimize hydrogen binding on electrocatalyst surface, accomplishing prominent HER activity in a wide pH range. The optimal Ni 2-x Co x P/N-C NFs afford low overpotentials ( η 10 ) of 100, 130 and 110 mV to reach a current density of -10 mA cm −2 in 0.5 M H 2 SO 4 , 1.0 KOH and 1.0 M PBS (phosphate buffer saline), respectively, performing among the best of noble-metal-free electrocatalysts. With a good functionality for oxygen evolution ( η 10 = 280 mV), such composite further delivers a high efficiency for overall water splitting, featuring a comparable cell voltage (1.56 V @ 10 mA cm −2 ) to a commercial IrO 2 /C − Pt/C couple, and remarkably better stability. Identifying electrocatalysis relying on solid-solution alloys, this work will inspire the exploration of cost-efficient electrocatalysts and the new understanding on catalytic mechanisms.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
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IF 4.084
Yang Hui Deng,Bai Xiang Tao,Cui Ye,Qing Zhang,Guo Chen,Xiao Hu Wang,Yan Shi,Jing Rong Chen,Hong Qun Luo,Nian Bing Li
Developing the cost-effective catalyst based on earth-abundant materials is a crucial demand for water oxidation . Doping heteroatom into catalysts is regarded as an effective strategy to regulate electronic configuration and improve the catalytic performance of water oxidation. In this work, N-doped CoS 2 on carbon cloth is fabricated by one-step synthesis, in which thiourea acts as both sulfur and nitrogen sources. The N-doped cobalt disulfide shows superior catalytic activity for oxygen evolution, with a low overpotential of 240 mV for 10 mA cm −2 , small Tafel slope (56 mV dec −1 ) and high turnover frequency due to the modification with electronic structure after incorporation of N atom. Moreover, the incorporation of N atom provides a distinctive perspective of doping other heteroatom into the material for modifying the electrochemical properties .
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2019
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IF 6.361
Zhefu Li,Binling Chen,Xianfeng Wang,Jun Nie,Guiping Ma
In this work, a novel catalyst of oxygen reduction reaction (ORR) was designed and fabricated by electrospinning, photo-curing and carbonization, based on polymer poly(dimethylsilylene ethynylenephenyleneethynylene) (PMSEPE) and metal organic frameworks (MOFs)—Materiaux de l'Institute Lavosier-101(Fe) (MIL-101(Fe)). The optimal catalyst PMSEPE/MIL-101(Fe)-800, which was carbonized at 800 °C, presented a bamboo-like nanofiber structure with a high degree of graphitization, a high specific surface area (302.3 m 2 /g) and a high yield (64.17%). Fe 3 C particles were found to be encapsulated into the Fe-Si-N co-doped carbon nanofibers. In the electrochemical tests, PMSEPE/MIL-101(Fe)-800 showed an onset potential of 0.935 V ( vs . RHE) and a diffusion limit current of 6.01 mA/cm 2 ( vs . RHE) in 0.1 M KOH aqueous solution, of which performances are competitive to commercial 20 wt% Pt/C. PMSEPE/MIL-101(Fe)-800 also exhibited a higher methanol tolerance and duration stability. Further Zn-air battery test used by PMSEPE/MIL-101(Fe)-800 suggested its potential for the application of fuel cell.
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Polymers
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2019
·Vol. 11
·期 2
·302
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IF 3.164
Boxiang Wang,Song Zhang,Yifan Wang,Bo Si,Dehong Cheng,Li Liu,Yanhua Lu
At present,Antheraea pernyisilk fibroin (ASF) has attracted research efforts to investigate it as a raw material for fabrication of biomedical devices because of its superior cytocompatibility. Nevertheless, native ASF is not easily processed into a hydrogel without any crosslinking agent, and a single hydrogel shows poor mechanical properties. In this paper, a series of ASF/poly (N-isopropylacrylamide) (PNIPAAm) composite hydrogels with different ASF contents were manufactured by a simple in situ polymerization method without any crosslinking agent. Meanwhile, the structures, morphologies and thermal properties of composite hydrogels were investigated by XRD, FTIR, SEM, DSC and TGA, respectively. The results indicate that the secondary structure of silk in the composite hydrogel can be controlled by changing the ASF content and the thermal stability of composite hydrogels is enhanced with an increase in crystalline structure. The composite hydrogels showed similar lower critical solution temperatures (LCST) at about 32 °C, which matched well with the LCST of PNIPAAm. Finally, the obtained thermosensitive composite hydrogels exhibited enhanced mechanical properties, which can be tuned by varying the content of ASF. This strategy to prepare an ASF-based responsive composite hydrogel with enhanced mechanical properties represents a valuable route for developing the fields of ASF, and, furthermore, their attractive applications can meet the needs of different biomaterial fields.Keywords:Antheraea pernyi;silk fibroin;hydrogel;thermosensitive;mechanical properties
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COMBUSTION AND FLAME
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2019
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IF 4.12
Luc-Sy Tran,Julia Wullenkord,Yuyang Li,Olivier Herbinet,Meirong Zeng,Fei Qi,Katharina Kohse-Höinghaus,Frédérique Battin-Leclerc
Di- n -butyl ether (DBE, C 8 H 18 O) has been proposed as a promising biofuel for diesel engines , but details of its low-temperature (LT) oxidation chemistry are not well understood. This paper reports new speciation data obtained in the temperature range of 400–1100 K at ϕ=1 and nearly-atmospheric pressure, using a plug flow reactor combined with electron ionization molecular-beam mass spectrometry (MBMS) and two different jet-stirred reactors coupled with either online gas chromatography or tunable synchrotron vacuum ultraviolet photoionization-MBMS. The experimental results confirm that DBE is very reactive and exhibits two negative-temperature coefficient (NTC) zones around 500–550 K and 650–750 K. Speciation data with about 40 C 0 -C 8 species are presented, including about 20 LT species not reported previously. Among those, fuel-specific C 8 H 16 O 2 cyclic ethers were quantified. Also, butanoic acid , which is present in highest amounts among the detected LT intermediates, and C 8 H 14 O 3 diones, were found to peak already near 500 K, suggesting their importance in the LT chemistry of DBE. Signals of several highly oxygenated peroxides ( e.g. , C 8 H 14 O 5 and C 8 H 16 O 6 ) were detected, indicating third O 2 addition steps. Respective reaction pathways are suggested and discussed based on these experimental results. To better understand the LT chemistry of DBE, the present data were compared to two recent DBE models (Cai et al., 2014; Thion et al., 2017). Significant discrepancies between the experimental data and both models were found for important LT intermediates, of which many were not included in the respective mechanisms. The results reported in the present study thus provide new opportunities for refining DBE kinetic models .
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Materials
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2018
·Vol. 11
·期 3
·354
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IF 2.467
Xinxin Liu,Tao Song,Minmin Chang,Ling Meng,Xiaohui Wang,Runcang Sun,Junli Ren
Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt %, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 °C to 56 °C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release.Keywords:carbon nanotubes;xylan-based hydrogels;mechanical property;thermo-sensitive properties
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Polymers
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2018
·Vol. 10
·期 2
·219
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IF 2.935
Xin Chen,Chi Zhang,Weidong Li,Lei Chen,Wusheng Wang
A key for the preparation of polyacrylate-based polyurethane is the synthesis of hydroxyl-terminated polyacrylate. To our knowledge, exactly one hydroxyl group of every polyacrylate chain has not been reported. The hydroxyl-terminated poly(butyl acrylate) (PBA) has been successfully synthesized by degenerative iodine transfer polymerization (DITP) of then-butyl acrylate (n-BA) using 4,4′-azobis(4-cyano-1-pentanol) (ACPO) and diiodoxylene (DIX) as initiator and chain transfer agent, respectively, and subsequently substituted reaction of the iodine-terminated PBA with β-mercaptoethanol in alkaline condition. The latter reaction was highly efficient, and the terminal iodine at the end of polymer chains were almost quantitatively transformed to a hydroxyl group. 2,2′-Azobis(isobutyronitrile) (AIBN) and ACPO were used as initiators in the DITPs ofn-BA. The results demonstrated that they had a significant influence on the terminal groups of the formed polymer chains. The structure, molecular weight, and molecular weight distribution of the hydroxyl-terminated PBA have been studied by1H,13C NMR, and GPC results. The components of hydroxyl-terminated PBA were determined by MALDI-TOF MS spectra, and their formation is discussed. The broad molecular weight distribution of the PBA and the difference in the polymerization behaviors from typical living radical polymerization are explained based on the results of1H NMR and MALDI-TOF MS spectra. The hydroxyl-terminated PBA has been successfully used in the preparation of PBA-based polyurethane dispersions (PUDs). The aqueous PUDs were stable, and based on the DSC results it can be said that the miscibility of hard segments with PBA chains was improved.Keywords:poly(n-butyl acrylate);degenerative iodine transfer;free-radical polymerization;waterborne polyurethane
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Nano Research
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2018
·Vol. 11
·期 3
·1500-1519
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IF 7.994
Qiao Mingtao,Lei Xingfeng,Ma Yong,Tian Lidong,He Xiaowei,Su Kehe,Zhang Qiuyu
Yolk–shell Fe 3 O 4 @N-doped carbon nanochains, intended for application as a novel microwave-absorption material, have been constructed by a three-step method. Magnetic-field-induced distillation-precipitation polymerization was used to synthesize nanochains with a one-dimensional (1D) structure. Then, a polypyrrole shell was uniformly applied to the surface of the nanochains through oxidant-directed vapor-phase polymerization, and finally the pyrolysis process was completed. The obtained products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and thermogravimetric analyses (TGA) to confirm the compositions. The morphology and microstructure were observed using an optical microscope, scanning electron microscope (SEM), and transmission electron microscope (TEM). The N 2 absorption–desorption isotherms indicate a Brunauer–Emmett–Teller (BET) specific surface area of 74 m 2 /g and a pore width of 5–30 nm. Investigations of the microwave absorption performance indicate that paraffin-based composites loaded with 20 wt.% yolk–shell Fe 3 O 4 @N-doped carbon nanochains possess a minimum reflection loss of −63.09 dB (11.91 GHz) and an effective absorption bandwidth of 5.34 GHz at a matching layer thickness of 3.1 mm. In addition, by tailoring the layer thicknesses, the effective absorption frequency bands can be made to cover most of the C, X, and Ku bands. By offering the advantages of stronger absorption, broad absorption bandwidth, low loading, thin layers, and intrinsic light weight, yolk–shell Fe 3 O 4 @N-doped carbon nanochains will be excellent candidates for practical application to microwave absorption. An analysis of the microwave absorption mechanism reveals that the excellent microwave absorption performance can be explained by the quarter-wavelength cancellation theory, good impedance matching, intense conductive loss, multiple reflections and scatterings, dielectric loss, magnetic loss, and microwave plasma loss.
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Inorganic Chemistry Frontiers
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2018
·Vol. 5
·期 9
·2211-2217
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IF 5.106
Xianghong Li,Xu Sun,Xiang Ren,Dan Wu,Xuan Kuang,Hongmin Ma,Tao Yan,Qin Wei
Electrochemical oxygen reduction is a key process for many energy storage and conversion devices, and finding highly efficient, economical, and durable electrocatalysts to replace the Pt-based catalyst for the oxygen reduction reaction (ORR) is a critical obstacle. In this article, porous Fe–N-codoped materials are obtained by pyrolysis of a defined precursor of polydopamine-coated Fe3O4 as not only template but also nitrogen and iron source. In 0.1 M KOH, the as-prepared catalyst exhibited high ORR activity (onset potential of 0.949 V and half-wave potential of 0.836 V vs. RHE), with excellent electrochemical stability, durability and remarkable tolerance toward methanol. The successful synthesis of porous nanospheres provides a novel way to explore a series of mesoporous metal electrocatalysts for energy conversion.
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
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2018
·Vol. 18
·期 6
·4196-4203
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IF 1.354
Wu Jinzhu,Feng Yaxiu,Shao Yanbin,Sun Yanchun
Nitrogen and silicon co-doped carbon nanodots (N/Si-CDs) were synthesized by one-step hydrothermal carbonization of folic acid and 3-aminopropyl trimethoxy silane with the assistance of glycerol. The resultant N/Si-CDs present intense excitation-independent photoluminescence (PL) emission
owing to their monodisperse sizes and specific surface states. In comparison to nitrogen single doped CDs (N-CDs), the co-doped N/Si-CDs possess better PL properties following different emission manner due to the synergistic effects of the nitrogen and silicon dopants. Besides, the functionalized
surfaces of N/Si-CDs endow them with superior solubility and stability. The as-synthesized N/Si-CDs demonstrate selective and sensitive fluorescence response to Fe3+, which could be explained by the PL quenching effects of Fe3+ on N/Si-CDs. Based on this finding, the
quantitative analysis of aqueous Fe3+ by N/Si-CDs was established, showing good linearity in a range of 10 nM~45 μM and good sensitivity with a detection limit of 3.8 nM, so did for the detection of Fe3+ in fetal bovine serum (FBS) spiked samples. Therefore,
the N/Si-CDs as a novel fluorescence probe hold promising for monitoring environmental and clinical Fe3+.
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NANO
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2018
·
IF 1.1
Jing Liu,Xiao Li,Xin Gong,Taiping Qing,Peng Zhang,Bo Feng
The incorporation of dopant atoms alters the structure of MoS 2 , resulting in unique properties and practical applications. Herein, a facile and low-cost approach for producing N-doped molybdenum disulfide (N-MoS 2 ) was carried out using melamine and MoS 2 in a laboratory tube furnace at 400 ∘ C for 2 h. The N-MoS 2 fluorescent probe showed sensitive response to Hg 2 + in a wide concentration range of 0.4–10 μ M with a low limit of 28 nM. The practical applicability of detecting Hg 2 + in lake water samples may open a new way to evaluate Hg 2 + in wastewater.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2018
·
IF 5.091
Jiaojiao Jiang,Zipeng Xing,Meng Li,Zhenzi Li,Junwei Yin,Junyan Kuang,Jinlong Zou,Qi Zhu,Wei Zhou
Plasmon Ag decorated 3D urchinlike N-TiO 2−x photocatalysts are successfully synthesized by a facile hydrothermal treatment (180 °C) and combined with a photo-deposition approach, followed by a reduction treatment. The results show that the resultant Ag/N-TiO 2−x sample possesses a three-dimensional (3D) urchinlike nanostructure with high crystallinity of anatase. Meanwhile, it exhibits the narrow optical band gap (Eg ∼ 2.61 eV) and the excellent visible-light-driven photocatalytic performance. Moreover, the hydrogen generation rate and photocatalytic degradation rate of phenol are up to 186.2 μmol h −1 g −1 and 97.7% under visible light irradiation, which are about 4.2 and 5.4 folds greater than that of N-TiO 2 . The mechanism of photocatalytic process is also proposed, and the enhanced photocatalytic property is mainly due to the synergistic reaction of the Ti 3+ and N codoping, which narrows the band gap and favors the utilization of visible light, and the plasmon effect of Ag nanoparticles and unique 3D urchinlike architecture, which are propitious to the separation and transmission of photogenerated carriers.
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