CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Fei Xie,Yang Chen,Minyu Bai,Pinglu Wang
In the present work, a Co-substituted LiZnTiBi (Li 0.43 Zn 0.27 Co x Ti 0.13 Fe 2.167-x Bi 0.003 O 4 ) ferrite with equivalent permeability and permittivity was prepared by a low-temperature sintering method. In detail, the LiZnTiBi ferrite with high permeability was obtained by a solid phase method. Next, different mass of Co 2 O 3 (x = 0.100, 0.125, 0.150, 0.175 and 0.200) were added to reduce permeability ( μ r ’ ) and enhance cut-off frequency ( f r ) of the ferrite. Results indicated that the Co-substituted LiZnTiBi ferrite with equivalent permeability and permittivity ( μ r ’ = ε r ’ = ∼12.3) was obtained when additive amount of Co 2 O 3 (x) is around 0.150. Meanwhile, the cut-off frequency ( f r ) of the ferrite is more than 500 MHz. Also, the influences of Co 2 O 3 additive on the microstructure and phase structure of the LiZnTiBi ferrite have been investigated and discussed. SEM images indicated that the Co-substituted LiZnTiBi ferrites possess uniform and compact grains (average grain size is ∼1 μm). XRD patterns demonstrated that the LiZnTiBi ferrite material has a pure spinel structure. Rietveld refinement of XRD proved that Fe 3+ is substituted by Co 3+ . And energy dispersive spectrometer (EDS) result indicated that the Co element is existed in ferrite grains. Such a low-temperature sintering ferrite substrate material with equivalent permeability and permittivity at high frequency (@500 MHz) should also be an alternative material for microwave devices, especially for miniature antenna.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
·
IF 3.375
Jianian Chen,Mingyu Chu,Fenglei Lyu,Jin Gong,Linzhong Wu,Lijia Liu,Yong Xu,Qiao Zhang
Two-dimensional (2D) metal carbides, carbonitrides, and nitrides (MXenes) have recently emerged as promising candidates in catalysis due to their unique properties. In this work, we composited Ti3C2 with Co-embedded N-doped carbon nanotubes (CNTs) via the pyrolysis of zeolitic imidazolate frameworks (ZIF-67) for propyne selective hydrogenation. Detailed characterizations show that strong synergistic effects are observed between the Ti3C2 and Co-embedded N-doped CNTs in the composite catalysts. This work provides an efficient strategy to achieve N-doping on Co nanoparticles, which play a vital role in the propyne selective hydrogenation. The optimized catalyst gives a high propyne conversion (∼99%) and high propene selectivity (∼96%) on propyne selective hydrogenation at 150 °C, which surpasses the reported non-noble metal catalysts in literature works. This work may not only open an avenue for obtaining active and selective catalysts for propyne selective hydrogenation but also promote research on the role of MXenes in catalysis.
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RSC Advances
·
2019
·Vol. 9
·期 58
·33997-34003
·
IF 3.049
Xiao Zhou,Haoran Yu,Yang Liu,Yong Kong,Yongxin Tao,Yong Qin
Co, Al and N tri-doped graphene (CANG) was successfully fabricated via annealing N-doped graphene with Co and Al precursors. The material was characterized by scaning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, physical adsorption, and X-ray photoelectron spectroscopy (XPS). It was found that the as-prepared CANG features a robust three-dimensional hierarchically porous structure. The contents of Co and Al can achieve the maximum value of 2.18 at% and 0.51 at% at the annealing temperature of 950 °C. Upon using the electrocatalyst for the hydrogen evolution reaction (HER), the CANG exhibited remarkable electrocatalytic performance in both acidic (η10 = 105 mV) and alkaline media (η10 = 270 mV), and outperforms Co,N-codoped graphene and Al,N-codoped graphene, respectively. In combination with the density functional theory (DFT) calculations, it was revealed that the introduction of the Al heteroatom can decrease the absolute value of hydrogen adsorption free energy (ΔG(H*)) of Co–N–C catalysts, thus greatly enhancing the HER activity. This discovery will provide new guidance to the design of advanced and inexpensive carbon materials for fuel cell, water-splitting and other electrochemical devices.
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PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2019
·
IF 7.015
Huayong Luo,Kelin Wu,Qin Wang,Tian C. Zhang,Hanxing Lu,Hongwei Rong,Qian Fang
We explore the feasibility of utilizing electro-responsive hydrogels as novel forward osmosis (FO) draw agents for desalination. The chemically cross-linked hydrogels were synthesized via free radical copolymerization of common acrylamide (AM) with strong anionic comonomer 2-acrylamido-2-methyl- 1 -propanesulfonic acid (AMPS). The morphology, chemical structure , water-adsorbing capacity, and water state of the hydrogels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), a swelling test, and differential scanning calorimetry (DSC). The water-swollen hydrogels exhibited electroresponsiveness as shrinking and expanding reversibly with the on-off switching of the electric field in an electrode contact system. The magnitude of hydrogels’ deswelling increased with the increase in the degree of swelling and applied voltages. This dehydration phenomenon was induced by the decrease in hydration power of microcounter ions due to the interaction with the electrodes by water electrolysis. The hydrogels were proved to be capable of generating a reasonable water flux of 2.76 L m −2 h −1 (LMH) from brackish water (2000 ppm NaCl solution) due to their high swelling pressure. In addition, the water flux was affected by the amount of hydrogel particles on the membrane surface. Importantly, the prepared hydrogels could effectively release around 71% of the adsorbed water at an applied voltage of 15 V for 40 min, and were able to maintain their water flux and water recovery performances up to three times regeneration. Results indicate that the electric field is an attractive alternative stimulus for extracting desirable water from the hydrogel draw agent in the FO desalination process.
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OPTICS AND LASER TECHNOLOGY
·
2018
·
IF 2.503
Qi Wang,Botao Wang
A sensitivity enhanced surface plasmon resonance (SPR) immunosensor based on Graphene oxide (GO) composite and staphylococcal protein A (SPA) co-modified photonic crystal fiber (PCF) is developed for human IgG detection. The PCF spliced between two section of multimode fibers (MMFs) is sputtered with gold film, which was then modified with graphene oxide and SPA for further immunosensing. Graphene oxide with abundant functional groups has a large surface area for more biomolecules immobilization and can enhance the interaction between Au film and external medium, leading to the sensitivity increased greatly. SPA can specifically bind the Fc region of the antibodies and has a high degree of orientation for capturing antibodies. Experimental results indicated that the refractive index (RI) sensitivity of graphene oxide modified Au-PCF SPR sensor reaches 4649.8 nm/RIU, which is about 1888 nm/RIU higher than that without graphene oxide film and the human IgG detection limit reaches as low as 10 ng/mL. Such a sensitivity enhanced immunosensor based on graphene oxide and SPA co-modified PCF shows a great promise in biosensing.
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高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
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2018
·Vol. 18
·期 6
·4196-4203
·
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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ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Mingquan Liu,Silu Huo,Min Xu,Linlin Wu,Mingjie Liu,Yifei Xue,Yi-Ming Yan
Nitrogen and sulfur co-doped carbon (NSC) is considered as a promising electrode material for supercapacitors (SCs). However, the specific capacitance and the rate performance of NSC are not satisfied for practical applications due to its inappropriate structural properties. Herein, we report the structural engineering of NSC by optimizing pore structure to obtain an ordered hierarchical pore network. The as-prepared NSC possesses a high gravimetric capacitance of 322 F g -1 at the current density of 1.0 A g −1 and retains 206 F g −1 (64% of its capacitance at 1.0 A g −1 ) at the high current density of 100 A g −1 . Moreover, it reveals an excellent cycling performance with ∼93.4% capacitance retention after 10000 cycles at the current density of 20 A g −1 . An assembled symmetric supercapacitor (SC) shows a remarkable energy density of 11.4 Wh kg −1 and a high power density of 12.9 kW kg −1 . The outstanding performances of NSC electrodes benefit from the efficient ion diffusion and fast charge transfer. This work paves a way to rationally design and engineer the structure of NSC for achieving both high rate capability and high specific capacitance for SCs applications.
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SOLID STATE IONICS
·
2019
·
IF 2.886
Hengxu Song,Yuhong Zhao,Yongqiang Niu,Hua Hou
Medium-temperature molten salt reserve primary cell utilizes low-melting nitrate electrolyte, that is considered suitable for geothermal borehole as well as oil and gas exploration . In this work, Cr 3+ and F − ions were introduced into spinel lithium manganate oxides by high-temperature solid-state method and verified by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of fluorine content on the morphology and discharge performance of the LiCr 0.1 Mn 1.9 O 4− x F x (0 ≤ x ≤ 0.5) have been studied in LiCr 0.1 Mn 1.9 O 4− x F x /LiNO 3 -KNO 3 -Ca(NO 3 ) 2 /Li-Mg-B system. Fluoride-doped samples have a significant improvement in discharge performance at the condition of 10 mA·cm −2 and 250 °C because of the stabilization of the crystal structure. Factors of operating temperature and current density have a significant effect on battery discharge performance, and the surroundings of 10 mA·cm −2 and 200–250 °C contributes the battery to achieve high performance. That indicates the LiCr 0.1 Mn 1.9 O 4− x F x /LiNO 3 -KNO 3 -Ca(NO 3 ) 2 /Li-Mg-B battery shows great potential in geothermal borehole as well as oil and gas exploration environment.
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Nano Energy
·
2018
·
IF 13.12
Qirui Liang,Huihui Jin,Zhe Wang,Yuli Xiong,Shuai Yuan,Xianci Zeng,Daping He,Shichun Mu
Developing low-cost, highly active, and stable bifunctional electrocatalysts is a challenging issue in electrochemical water electrolysis . Herein, we develop a simple metal organic frameworks (MOFs) based approach to prepare bifunctional Co-NC@ Mo 2 C complex catalysts. Differently from traditional carbon encapsulated functional nanomaterials , herein the carbon-based framework derived carbonitride and Co nanoparticles (Co-NC) are encapsulated with Mo 2 C. Benefiting from the unique reverse-encapsulation structure and synergetic effects of Mo 2 C and Co-NC, the Co-NC@Mo 2 C catalyst shows superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance. In alkaline media , it affords the current density of 10 mA cm −2 at low overpotentials of 99 mV and 347 mV for HER and OER, respectively. Interestingly, due to a reversed encapsulation structure where Co nanoparticles are protected by Mo 2 C, it leads to an outstanding HER catalytic activity (a low overpotential of 143 mV) and stability in acidic solutions. Remarkably, when employed as both the cathode and anode for overall water splitting, a low cell voltage of 1.685 V is required to reach the current density of 10 mA cm −2 in alkaline media with excellent stability, making the Co-NC@Mo 2 C an efficient non noble metal bifunctional electrocatalyst toward water splitting.
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Analytical Methods
·
2018
·Vol. 11
·期 4
·415-420
·
IF 2.073
Tianli Wang,Xue Hu,Xiaodan Zhang,Haiyan Cao,Yuming Huang,Ping Feng
Photoluminescence probes based on a conventional Fenton system show unsatisfactory sensitivity due to low H2O2 decomposition efficiency. Herein, we report that molybdenum disulfide quantum dots (MoS2 QDs) show excellent co-catalytic activity for Fenton reactions due to the Mo4+ active sites on their surfaces facilitating Fe(III)/Fe(II) cycle reactions and high H2O2 decomposition efficiency. The MoS2 QDs were prepared by a simple hydrothermal method, and the obtained MoS2 QDs showed blue fluorescence with a high quantum yield of 13.4%, storage stability, and excellent water-solubility. By using bifunctional MoS2 QDs acting as both the fluorescent probe and the Fenton catalyst, a MoS2 QDs co-catalytic Fenton sensor system was proposed for ultrasensitive and selective fluorescence sensing of H2O2 with a linear range from 0.01 to 20 μM and a detection limit of 5 nM (S/N = 3). When coupled with glucose oxidase, glucose can be detected in the range of 0.01–30 μM with a detection limit of 7 nM. Moreover, we successfully demonstrated the potential application of the proposed system for glucose sensing in actual biological samples. The novel strategy proposed in this work may open a new window of interest in an unconventional application of MoS2 QDs-Fenton sensor platform for environmental and biological applications.
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ACS Omega
·
2018
·
IF 0
Guorong Gao,Liufang Wang,Yang Cong,Zhenwu Wang,Yang Zhou,Rong Wang,Jing Chen,Jun Fu
Hydrogel actuators that deform in response to external stimuli have promising applications in diverse fields. It is desirable to develop robust hydrogels with multiple and synergistic stimuli responsiveness. This work reports on robust poly(NIPAM-co-DMAPMA)/clay hydrogel bilayers that undergo reversible and repeatable curling/uncurling in response to pH and/or temperature changes. The bilayers are fabricated by sequential synthesis of thermoresponsive N-isopropylacrylamide (NIPAM) and N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) monomers, which produces robust interface bonding between the layers. Different NIPAM/DMAPMA ratios were used between two gel layers to manipulate the asymmetric responsiveness, thus leading to curling/uncurling of bilayers upon exposure to stimuli. The hydrogel bilayers are fabricated into soft manipulators to grasp and release target objects by pH and temperature changes, and as artificial muscle to lift and move a hanging weight by synergistic pH and temperature stimuli. This work provides a new type of asymmetric responsive hydrogel bilayer with potential applications in biomimetic actuators.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2018
·Vol. 124
·期 6
·1-8
·
IF 1.604
Lin Changwei,Tang Yu,Song Jun,Han Lei,Yu Jingbo,Lu Anxian
In the present study, series of garnet-type Li 6.75+ x La 3− x Sr
x
Zr 1.75 Nb 0.25 O 12 solid electrolytes [LLSZN with various Sr contents ( x = 0.05–0.25)] have been prepared via conventional solid-state method. The effects of Sr contents on their phase structure and ionic conductivity have been systematically investigated on the combined measurements of X-ray diffraction and scanning electron microscopy and alter current impedance spectroscopy. Our results reveal that a phase transition from tetragonal to cubic structure occurs when both Sr and Nb elements is introduced, and such a cubic structure can be stable over the whole Sr contents variation, which is suggested to provide a beneficial impact on the performance of LLSZN. Accordingly, both relative density and total ionic conductivity exhibit a favorable tendency of increasing first and then decreasing with increased Sr contents, wherein a peak value at 93.46% and 5.09 × 10 −4 S cm −1 , respectively, can be well achieved. Particularly, the maximum ionic conductivity is almost twice that of the compared sample (2.93 × 10 −4 S cm −1 ), and possess the minimum activation energy ~ 0.30 eV. Such a modification method, featured with higher efficiency and lower cost, is expected to be helpful for the development of solid electrolyte.
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