INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Tianlun Cen,Lijun Qiu,Zhifeng Ye,Xiaomin Peng,Yiyi Liu,Dingsheng Yuan
The development of transition-metal electrocatalyst is of great importance to bring down costs and enhance performance for fuel cells and water splitting. The multiple efforts have been concentrated on bifunctional electrocatalysts toward hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Only a few works reach desirable durability and performance levels. Here, Co/VN heterostructure with rational porous structure is formed in response to the sensible cobalt and vanadium ratio. Owing to synergistic interaction of holey interconnected structure with large surface area of 57 m 2 g −1 and abundant interfaces between Co and VN phases, Co/VN@NC presents superior bifunctional electrocatalytic performance towards both HER and ORR. Co/VN@NC drives the reaction with low overpotential η 10 of 96 mV and Tafel slope of 82 mV dec −1 along with outstanding stability for HER. Furthermore, Co/VN@NC obtains an onset potential (0.954 V) and half-wave potential (0.796 V) with superior methanol tolerance and durability for ORR.
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CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Yuchen Zhang,Yongqian Shen,Minmin Dang,Fan Zhang,Xueyan Du
Carbon nanofiber composites could be used as a microwave absorbing candidate owing to its lightweight and dielectric properties . In this work, the carbon-based nanofibers were synthesized using cobalt acetate tetrahydrate (CoAc)/poly (vinyl alcohol) (PVA) as a precursor solution via the electrospinning and vacuum carbonization at 650 °C. Co and CoO were simultaneously introduced into carbon nanofibers (CNFs). The CNFs absorber with an especially low filling ratio of 10% exhibited excellent microwave absorbing properties. The minimum reflection loss (RL) reached −43.57 dB at 10.48 GHz with a matching thickness of 3 mm, and the wideband effective absorption (RL ≤ −10 dB) reached 5.78 GHz (10.94–16.72 GHz) at 2.5 mm. The superior absorption performance of the as-prepared CNFs resulted from the formation of CoO, causing the improvement of impedance matching and interfacial polarization. Besides, the CNFs displayed good hydrophobicity due to the roughened surfaces. These newly synthesized Co/CoO/CNFs might be considered as a prospective candidate for highly efficient microwave absorption materials with a self-cleaning function.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
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IF 16.683
Yifan Li,Chang Chen,Rui Cao,Ziwei Pan,Hua He,Kebin Zhou
Electrochemical reduction of CO 2 into value-added carbon compounds offers a promising strategy to mitigate global warming, but present challenges for chemistry due to the poor selectivity and stability of electrocatalysts. In this work, we report a dual-atom Ag 2 /graphene catalyst featuring well-defined AgN 3 -AgN 3 active site for CO 2 electrochemical reduction. This dual-atom catalyst can drive CO 2 reduction reaction at a potential as high as -0.25 V, and exhibit excellent CO Faradic efficiency up to 93.4 % with a current density of 11.87 mA cm −2 at -0.7 V and long-term stability, far surpassing the single-atom Ag 1 /graphene and the traditional silver nanoparticle catalysts. DFT calculations reveal that the dual-atom Ag site lowers the barrier for the formation of *COOH by stabilizing the *CO 2 through the concomitant interactions with the C and an O atom of CO 2 , resulting in excellent catalytic performance.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
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IF 5.162
Zhengyi Zhang,Jiaoman Li,Yan Zhang,Zhenfu Jin
Lignin, which is crosslinked by ether and carbon‑carbon linkages, is a highly branched polymer consisting of phenyl propane units. And owing to the abundant phenolic hydroxyl groups and its structural heterogeneous characteristics, lignosulfonate, considered as a renewable aromatic macropolymer, can be used as co-curing agent in EP thermoset systems. In this study, kinetics of lignosulfonate (LS) and partially depolymerized lignosulfonate (DLS) as co-curing agents for applications to EP thermoset were discussed with the differential scanning calorimetry (DSC) measurement. The activation energy ( E a ) and dynamic modeling of curing reaction were obtained by the methods of non-isothermal kinetic analysis reported by Kissinger and Ozawa. The glass transition temperature ( T g ) was determined by DSC and mechanical properties of epoxy resins were carried out using the Universal Testing Machine. The LS dropped the exothermic peak temperature and E a of curing reaction of EP thermoset. Those of DLS were more active than the higher molecular weight lignosulfonate. The EP thermoset cured with DLS (EP-DLS) exhibited much higher reactivity, and the curing reaction could be occurred at lower temperature. The T g of EP-DLS has risen by 10 °C compared with the case without lignosulfonate. The tensile strength , elongation at break and impact strength of EP-DLS rose by 28.7%, 52.5% and 53.5%, respectively, than those of the epoxy resin cured with LS (EP-LS).Molecular weight of lignosulfonate could be an important factor of the curing reaction of EP thermoset. The high performance EP thermoset could be obtained by partially depolymerized lignin as co-curing agents.
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MICROCHIMICA ACTA
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2020
·Vol. 187
·期 2
·1-8
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IF 6.232
Hou Chuantao,Zhang Xueli,Wang Lei,Zhang Fan,Huang Xiaolian,Wang Zonghua
A freestanding and flexible buckypaper modfied with CoP/Co (CoP/Co-BP) is described. It has a sponge-like nanostructure and is shown to enable improved nonenzymatic sensing of glucose. The CoP/Co-BP was prepared by first depositing a uniform layer of ZIF- 67 crystals on BP, followed by two steps of pyrolysis treatment and phosphidation under an argon atmosphere. The morphology and structure of the material were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties were investigated by cyclic voltammetry and amperometric response. The amperometric sensor, best operated at 0.45 V (vs. SCE) at pH 13 has a linear range that extends from 0.5 μM to 1.8 mM of glucose, a 0.2 μM detection limit (at S/ N = 3), and a sensitivity of 6427 μA mM −1 cm −2 in alkaline solution. This is mainly attributed to the synergistic effect between the highly active CoP nanostructure and BP which results in excellent conductivity. The uniformly distributed CoP nanoparticles in the network of BP prevent the formation of close-packed structure and facilitate electron transfer. The sensor has good selectivity and excellent long-term stability. It was applied to the determination of glucose in spiked human serum, and satisfactory results were obtained.
Schematic presentation of a freestanding and flexible buckypaper modfied with CoP/Co. It has a sponge-like nanostructure and exhibits improved catalytic activity toward glucose oxidation. This material was used for high-performance electrochemical glucose sensing.
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JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 55
·期 24
·10878-10895
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IF 3.553
Qiao Liyuan,Liu Cheng,Liu Chengde,Cheng Xitong,Li Yizheng,Wang Chenghao,Jian Xigao
Hydrogels find a variety of uses across various fields, but their development might be limited by their high-cost, toxic chemical crosslinking and complicated reactions. To address these issues, we developed a tough, high-strength hydrogel of polydiacetone acrylamide-co-poly(acrylamide), prepared using acrylamide, diacetone acrylamide (DAAM) and ammonium persulfate in a one-step reaction. The multiple physical crosslinking networks endow hydrogel with excellent overall properties given appropriate DAAM levels. The tensile modulus, fractured strain, fractured stress and toughness of the developed D 1 A 9 hydrogel are, respectively, as high as 0.15 MPa, 21 mm/mm, 0.71 MPa and 7 MJ/m 2 . Its compressive modulus under a strain of 80% is 0.088 MPa, while its shear modulus at a shear frequency of 100 Hz is 0.071 MPa. At the same time, D 1 A 9 hydrogel exhibits a high self-recovery efficiency of 50% during two continuous cyclic tensile tests, with the efficiency increasing to 65% for hydrogel incubated at 50 °C for 2 h. Finally, cytocompatibility and excellent drug-releasing behavior of the hydrogel make it a candidate for biomedical use.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2020
·Vol. 27
·期 21
·26810-26816
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IF 3.056
Chen Ying,Wang Yue,Zhou Xiaohan,Zhao Yang,Peng Wenchao
Synthesis of highly efficient photocatalysts for energy and environment catalysis is still a big challenge in the materials field. Cadmium sulfide (CdS) is a promising visible light-driven photocatalyst, which can be composited with co-catalysts to increase its photo-activity and stability. In this study, a kind of graphene material with abundant structure defects (D-rGO) is synthesized by a two-step annealing process with nitrogen-doped rGO (N-rGO) as an intermediate. The high-temperature annealing could remove the doped heteroatoms to form structure defects with five or seven carbon atoms. The D-rGO is then used as co-catalyst for the modification of CdS nanoparticles, and enhanced photocatalytic activities could be obtained. A large hydrogen evolution rate of 102.7 μmol h −1 g −1 is achieved, which is also effective for 4-nitrophenol reduction with a rate constant of 0.168 min −1 . The novel CdS/D-rGO composite contains no noble metals and could be used as multi-functional photocatalysts, thus should has great potential in the photocatalysis field.
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SURFACE ENGINEERING
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2020
·
IF 2.433
Zhen He,Di Cao,Yuxin Wang,Li Yin,Muhammad D. Hayat,Harshpreet Singh
A series of Co–P–TiO2 nanocomposite coatings were prepared via pulsed electrodeposition technique. TiO2 nanoparticles were embedded into the coating matrix using TiO2 sol. The phase constituents of nanocomposites were identified using X-ray diffraction. The surface morphology of nanocomposites was obtained through scanning electron microscopy. Wear tests and corrosion tests were conducted to determine the coating performance. Electrochemical characterization was performed by electrochemical impedance spectroscopy analysis. The nanocomposite coatings made via conventional pulse electrodeposition had a relatively ordered surface morphology and enhanced mechanical behaviour, which is associated with the increased strengthening effect of embedded nanoparticles. When applying a pulse reverse current, the Co–P–TiO2 nanocomposite coating had improved corrosion resistance owing to its smooth and uniform surface morphology.
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JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 55
·期 27
·13216-13231
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IF 3.553
Huang Liqu,Wang Xianli,Zhang Yue,Cheng Zhaojun,Xue Feng,Guo Yunfei,Deng Yongji,Chu Chenglin,Tao Li,Bai Jing
Hypospadias is a common congenital malformation of the male urogenital system. As a recently arisen reconstruction method for hypospadias, polymer tissue engineering urethral scaffold often results in necrosis and other complications due to the lack of bioactivity. To improve the bioactivity of polymer, in this work, we prepared biodegradable Mg/poly(lactic-co-glycolic acid) (PLGA) composite nanofiber scaffolds by electrospun with 3, 6, and 9 wt.% of micron-scale Mg particles. The mechanical properties of the PLGA scaffold gradually decrease with the addition of Mg particles but still at an acceptable level. On the other hand, these composite scaffolds show very good biocompatibility and promotional bioactivity, namely non-cytotoxicity, gradual proliferation enhancement, and good adhesion state of human adipose stem cells (HADSCs) on the scaffold surface. Besides, through quantitative real-time polymerase chain reaction (qRT-PCR) test, different genes expression levels of human umbilical vein endothelial cells (HUVECs) were also gradually up-regulated with the increase in Mg content. The present results indicate that Mg containing PLGA scaffolds might not only have the potential to promote tissue regeneration related to urethral repair, but also stimulate endothelial cells to achieve vascularization and anti-inflammatory functions. Consequently, considering both the mechanical properties and bioactivity for clinical demand, the Mg/PLGA composite scaffolds with suitable Mg contents are promising for the regeneration of defective urethral tissues.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 12
·6847-6859
·
IF 3.502
Yan Sun,Fei Yu,Meisong Liao,Juping Ma,Xin Wang,Dongbing He,Weiqing Gao,Jonathan Knight,Lili Hu
In this work, we systematically study the spectroscopic properties of Tb 3+ /Dy 3+ co-doped phosphate glasses in the visible spectral region and explore the sensitization role of Dy 3+ in the enhancement of visible fluorescence of Tb 3+ ions. Judd-Ofelt parameters Ω 2 and Ω 4 /Ω 6 of the phosphate glass as host for Tb 3+ are calculated as 21.60 × 10 -20 cm 2 and 0.73, respectively, based on the measured spectral absorption. Multiple energy transfer (ET) routes from Dy 3+ to Tb 3+ and their efficiencies are characterized, and the enhanced fluorescence properties of Tb 3+ are investigated, including the emission spectral strength and the spontaneous emission lifetime as functions of Dy 3+ doping concentration. The efficient nonradiative ET processes between Dy 3+ and Tb 3+ allow a moderate concentration level of Tb 3+ to achieve favorably stronger spectral absorption at blue and ultraviolet wavelengths. Tb 3+ /Dy 3+ co-doped phosphate glass shows promising potential for phosphors and lasing operation at visible wavelengths.
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RENEWABLE ENERGY
·
2019
·
IF 5.439
Qing-Lu Song,Yun-Peng Zhao,Fa-Peng Wu,Guo-Sheng Li,Xing Fan,Rui-Yu Wang,Jing-Pei Cao,Xian-Yong Wei
Low aromaticity and a large number of oxygen-bridged bonds among the aromatic structural units of lignin make it possible to obtain chemicals directly. A novel Co/ [email protected] catalyst with high activity towards hydrogenolysis of lignin-derived aryl ethers was synthesized according to the pyrolysis process of a predesigned ZIF-67. According to the results of characterization by powder X-ray diffraction (XRD), N 2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), Co was reduced by the carbonized organic linker of ZIF-67, and N was doped into the carbon skeleton of the catalyst. The effects of holding time, temperature, and initial H 2 pressure on the catalytic performance of Co/ [email protected] were evaluated in the selective hydrogenolysis of benzyl phenyl ether (BPE). BPE was completely converted and the selectivity of monomer reached to 98.2% under optimized reaction conditions. The C alk -O bond in BPE was first dissociated to form toluene and phenol, and then phenol was rapidly hydrogenated to form cyclohexanol. Furthermore, the Co/ [email protected] catalyst shows high activity for hydroprocessing and selective cleavage of other lignin-derived aryl ethers, including phenylethyl phenyl, diphenyl ether, dibenzyl ether, dinaphthalene ether, guaiacol, anisole and veratrole.
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BIOSENSORS & BIOELECTRONICS
·
2019
·
IF 9.518
Yongze Xie,Min Zhang,Qianyun Bin,Shilei Xie,Lu'an Guo,Faliang Cheng,Weizhong Lv
The fast and accurate detection of Carcinoembryonic Antigen (CEA) plays an important role in clinical cancer treatment and therapy. An ultrasensitive photoelectrochemical (PEC) immunosensor for the detection of CEA was constructed using CdSe@BiVO 4 co-sensitized TiO 2 nanorods as photoactive materials. TiO 2 nanorods were assembled on the FTO modified electrode to immobilize capture antibodies. With a sandwich immunoassay format, CEA and signal antibodies labelled CdSe@BiVO 4 were introduced in sequence via specific immunoreaction, and the ultrahigh sensitivity of this immunoassay results from the following three aspects. Firstly, the co-sensitization of BiVO 4 and CdSe extends the absorption range of TiO 2 from ultraviolet region to visible light region, which can adequately utilize the light energy; Secondly, the effective matching of energy levels among TiO 2 , CdSe and BiVO 4 accelerates the separation and transfer of photogenerated electron-hole pairs and significantly improves the PEC performance; Finally, the introduced Au evidently expedites the interfacial electron transfer from TiO 2 to FTO electrode, further resulting in noticeably increased photocurrent . Based on multiple signal amplification strategy, a largely linear detection range from 0.01 ng mL −1 to 50 ng mL −1 with a low detection limit (0.5 pg mL −1 ) were obtained. In addition, the prepared immunosensor with attractive properties provides a promising platform for PEC detection.
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