NEW CARBON MATERIALS
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2023
·
IF 5.7
Jing-yi Niu,De-qi Jing,Xing-hua Zhang,Wei-guo Su,Shou-chun Zhang
Hollow porous carbon fibers for Li-S battery electrodes were prepared by the KOH activation of carbon prepared from hollow polyacrylonitrile fibers. The fibers had a high specific surface area of 2 491 m 2 ·g −1 , a large pore volume of 1.22 cm 3 ·g −1 and an initial specific capacity of 330 mAh·g −1 at a current density of 1 C. To improve their electrochemical performance, the fibers were modified by treatment with hydrazine hydrate to prepare nitrogen-doped hollow porous carbon fibers with a specific surface area of 1 690 m 2 ·g −1 , a pore volume of 0.84 cm 3 ·g −1 and a high nitrogen content of 8.81 at%. Because of the increased polarity and adsorption capacity produced by the nitrogen doping, the initial specific capacity of the fibers was increased to 420 mAh·g −1 at a current density of 1 C.
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Journal of Environmental Chemical Engineering
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2023
·
IF 7.7
Qiang Li,Lijie Wang,Jupu Song,Linshen Zhang,Chunfeng Shao,Hong Li,Hemin Zhang
Construction of heterojunction photocatalysts is a valid tactics to boost the photocatalytic property of catalyst. Herein, a novel S-scheme heterojunction of zero/three dimensional (0D/3D) In 2 S 3 /Bi 2 WO 6 hybrid catalyst was obtained by assembling In 2 S 3 nanoparticles on floriated shaped Bi 2 WO 6 microsphere through a simple precipitation route for the first time. The morphology, structures, composition, chemical and optical properties of the resulting materials were carefully researched through various instruments. The degradation experiments revealed that In 2 S 3 /Bi 2 WO 6 composites exhibited superior photocatalytic behavior for dyes decomposition. The optimized In 2 S 3 /Bi 2 WO 6 composite showed remarkable photocatalytic decomposition Rhodamine B (RhB) and Methylene blue (MB), 16.0 (2.68)-fold and 70.3 (1.66)-fold larger than that of pristine Bi 2 WO 6 (In 2 S 3 ), and it also possessed good stability and reusability. The largely improved photoactivity may derive from the formed S-scheme heterojunction between Bi 2 WO 6 and In 2 S 3 , which accelerated photocarriers disassociation and retained strong redox power. Liquid chromatography-mass spectrometry (LC-MS) was applied to reveal the RhB decomposition pathway. Besides, the S-scheme charge transfer mechanism was well elucidated based on in-situ X-ray photoelectron spectroscopy analysis, density functional theory calculation (DFT), and trapping experiment along with electron paramagnetic resonance (EPR) tests.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Honghong Lei,Peng Jiang,Bin Li,Yuncheng Zhou,Rui Zhang,Jianlei Kuang,Wenbin Cao,Wei Wang
The (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are successfully obtained by mixing the Ba 2 In 2- x Cr x O 5+ y oxides and thiourea through a simple ball milling method followed by sintering at 400 °C for 3 h. The colors of the compounds change from orange-brown to yellow-green after reacting with thiourea. When Cr amount is small ( x = 0.1), the crystal structure of (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y is orthorhombic Ba 2 In 2 O 5 phase. When x ≥ 0.3, the crystal structure of the sample is cubic BaInO 2.5 phase. And this phase transition is the same as Ba 2 In 2- x Cr x O 5+ y . XPS results reveal that Cr 6+ in Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are reduced to Cr 3+ after sintering. S exists in both cation and anion forms, and N exists in substitutional forms. UV–Vis analysis indicates that the yellow-green hue comes from the d-d transition of Cr 3+ , and the doping of S, N ions leads to a red shift of the absorption edge of the samples.
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ADVANCED SYNTHESIS & CATALYSIS
·
2019
·Vol. 361
·期 13
·3191-3199
·
IF 5.451
Shuyun Ju,Mingxin Qian,Gang Xu,Lirong Yang,Jianping Wu
Optically pure 1,2,3,4-tetrahydroisoquinoline carboxylic acids constitute an important class of building blocks for the synthesis of natural products and synthetic pharmaceuticals. However, redox deracemization of racemic 1,2,3,4-tetrahydroisoquinoline carboxylic acids as an attractive method is still challenging for the lack of suitable oxidoreductases. Herein, a D-amino acid oxidase from Fusarium solani M-0718 ( Fs DAAO) with broad substrate scope and excellent enantioselectivity was exploited through genome mining, and applied for the kinetic resolution of a number of racemic 1- and 3-carboxyl substituted tetrahydroisoquinolines to yield the corresponding ( S )-enantiomers with excellent enantiomeric excess ( ee ) values (up to >99%). By using Fs DAAO in combination with ammonia-borane in one pot, deracemization of these racemic carboxyl-substituted tetrahydroisoquinolines was achieved with conversions up to >98% and >99% ee . Preparative-scale deracemization of racemic 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid and 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid was also demonstrated with good isolated yields (82% and 73%, respectively) and ee >99%. Our study provides an effective method for the synthesis of enantiomeric pure 1,2,3,4-tetrahydroisoquinoline carboxylic acids. This method is expected to provide access to chiral carboxyl-substituted 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydro-ß-carbolines.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
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IF 4.175
Yinglin Yan,Mangmang Shi,Yiming Zou,Yiqi Wei,Liping Chen,Chaojiang Fan,Rong Yang,Yunhua Xu
It had been proven that carbon aerogel (CA) can effectively improve the conductivity of sulfur (S) and suppress the shuttle effect of polysulfides in Li-S batteries, due to its outstanding electrical conductivity and micropore-rich structure. However, the microstructure of CA was easy to collapse and shrink during carbonization, resulting in a dramatically drop in specific surface area and porosity. Herein, graphene nanosheets (GNs) were introduced in CA to reinforce the structural stability. As-prepared CA/GNs composites were fabricated from in-situ polymerization of resorcinol (R) and formaldehyde (F) in graphene oxide (GO) solution. It was found that the mass concentration of the GO solution had a significantly positive effect on hierarchical porous structure of the CA/GNs composites, which presented improve the electrochemical performances due to the combination of micro-, meso- and macro-pores. It is worth noting that the CA/GNs0.1 sample, obtained from 10 wt % GO solution, possessed the largest specific surface area of 665.477 m 2 g −1 and the largest pore volume of 0.912 cm 3 g −1 . Especially, after incorporated with moderate amount of S (58.86 wt %), the CA/GNs0.1/S cathode exhibited the best electrochemical performances (initial discharging capacity of 1501 mAh g −1 at 0.1C and reversible capacities of 471 mAh g −1 after 100 cycles and 341 mAh g −1 after 500 cycles at 1C). This was attributed to the tunable hierarchical porous microstructure of the CA/GNs0.1 sample. Unfortunately, when increased the S content to 68.39 wt %, the electrochemical performance deteriorated in all aspects because of their sluggish reaction kinetics. These all results suggested that introducing GNs can feasibly enhance the performance of CA as matrix in Li-S batteries.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2019
·Vol. 21
·期 44
·24308-24315
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IF 3.567
Leipeng Li,Xudong Qi,Feng Qin,Lu Li,Hong Gao,Yangdong Zheng,Zhiguo Zhang
A guideline for designing sensitive thermometry is proposed. It reveals that using two emission bands that possess the opposite change tendencies against temperature makes it easier to achieve a larger relative sensitivity. Based on the guidelines, a highly sensitive strategy for optical thermal detection that depends on the Tb3+-to-Eu3+ emission ratio is designed by exciting Eu3+/Tb3+'s unusual absorption lines. This can be easily driven by a commonly used and cheap 405 nm laser diode. Moreover, its maximum relative sensitivity reaches up to 2.02% K−1 at 610 K, one of the largest sensitivities reported so far.
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高影响因子
ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Jiaona Shi,Qi Kang,Yan Mi,Qingquan Xiao
Lithium-sulfur (Li–S) batteries have attracted extensive attention in the past decades owing to their high theoretical energy density, low-cost and eco-friendliness. However, poorly cycling stability and rapidly decay caused by shuttle effects at high-sulfur loading condition restrain their practical applications. Focusing on these issues, N-doped hollow porous carbon nanotubes (N-HPCNT) as a self-supporting sulfur cathode is developed. The inherent conductivity and abundant pores of 3D continuous framework not only allow a high-sulfur content (67 wt%) and block the polysulfides via physical confinement, but also trap the polysulfides by the nitrogen heteroatoms (4.60 wt%) via strong chemisorption . Benefiting from the above-mentioned merits, the self-supporting S/N-HPCNT cathode with 3 mg cm −2 sulfur delivers high reversible capacity, super rate capability (1152 and 852.8 mAh g −1 at 0.2 and 3 C, respectively) and long cycling stability (717.9 mAh g −1 after 500 cycles at 1 C). Even under a higher sulfur loading (8 mg cm −2 ), it still exhibits a stable areal capacity of 7.72 mAh cm −2 (corresponding to 965.1 mAh g −1 ) after 60 cycles. This work provides a pathway for developing high performance Li–S batteries.
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POLYMER
·
2019
·
IF 3.771
Longfei Li,Hong Zhai,Tao Wang,Xibo Qiu,Na Qiang,Peng Dong,Ying Bai,Ai-Yun Peng,Daping Quan
The ring-opening copolymerization of lactide with carbonate is an available strategy to incorporate reactive groups to the pendent sites of copolymer for further functional modification. A series of random and block copolymers were synthesized from l -lactide ( L -LA) and 2-bromomethyl-2-methyltrimethylene carbonate (BMTC) using dodecanol as initiator and stannous octoate as catalyst. The structures of the copolymers were characterized by nuclear magnetic resonance ( 1 H NMR, 13 C NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The composition of the copolymers can be controlled through changing the feed ratios of n BMTC / n L -LA . It was found the random P(BMTC- co - L LA) copolymers had the semicrystalline characteristic due to the relative long block-like segments of P L LA ( L L , P L LA = 5.3–7.3) and the polar interactions from bromo groups , but their crystallinity ( X c, P L LA ) and melting temperature ( T m, P L LA ) decreased when the BMTC content increased. The X c, P L LA and T m, P L LA of P(BMTC- b -P L LA) block copolymers were relatively higher than the corresponding random copolymers, and approached gradually to the pure P L LA with the increase of the molecular weight of P L LA block. Finally, the pendent bromo groups of P(BMTC- co - L LA) were easily transformed into azides , which could proceed the azide-alkyne click reaction smoothly and quantitatively at room temperature .
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Qian Zhang,Wan Huang,Jun-ming Hong,Bor-Yann Chen
As the efficiency of electrocatalysis is depended on the characteristics of anode materials, heteroatom doping was applied to improve the physicochemical, electromagnetic, and structure properties of grapheme considering that the efficiency of electrocatalysis depends on the characteristics of anode materials. However, the mechanism underlying efficiency promotion remains unclear due to the complicated doping species of heteroatom. Single-form S loaded S/graphene/Pt/TiO 2 (S-GN/Pt/TiO 2 ) was prepared for the first time by using radical as precursor to clarify the function of S doping. The catalytic center for direct (pollution oxide on anode) and indirect electro-oxidation (pollution oxide by radicals) was then confirmed by density functional theory (DFT) calculation. Results indicated that C atom besides SOx is the active site for direct oxidation of acetaminophen (APAP), and SOx is the active site for indirect oxidation for the generation of HO . Furthermore, the effect of some parameters (such as S content, pH, applied current, temperature) and oxidants generated through different electrolytes were also completely deciphered in this study. GC–MS analysis was implemented to identify intermediates of APAP after electro-oxidation (i.e., eight types of intermediates identified) and the possible pathway of degradation was proposed. The single form S doping approach and S function discussion could provide the in-depth understanding to the mechanism of electrocatalysis and suggesting performance of related materials with practical values for applications.
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ACS Applied Energy Materials
·
2018
·
IF 0
Xiaorong Gan,Lawrence Yoon Suk Lee,Kwok-yin Wong,Tsz Wing Lo,Kwun Hei Ho,Dang Yuan Lei,Huimin Zhao
The phase transition of multilayer MoS2 nanosheets from semiconducting 2H to metallic 1T (2H/1T) has been realized mainly by chemical methods (e.g., Li intercalation). Here, we develop a simple yet effective method, cyclic voltammetry, to successfully tune the 2H/1T phase transition of multilayer MoS2 nanosheets without using intercalation species. The phase transition is triggered by the electrochemical incorporation of S vacancies (obtained by electrochemical etching), which on the one hand injects electrons into the framework of S–Mo–S and on the other hand facilitates the sliding of S planes. Density functional theory calculations show that O doping in the framework of S–Mo–S decreases the energy barrier for forming S vacancies and stabilizes the 1T-phase by occupying the 4d orbital of Mo. Our calculations further show that the presence of S vacancies and O incorporation not only reduces the bandgap of MoS2, indicating an increased conductivity, but also decreases the hydrogen adsorption free energy, implying significant improvement of hydrogen evolution reaction (HER) activity. Indeed, the overpotential and Tafel plot of the electrochemically treated MoS2 nanosheets are decreased respectively by 174 mV and 25 mV/dec at a cathodic current density of 10 mA cm–2 compared with pristine 2H-MoS2 nanosheets. The HER experiment also reveals the order of catalytical activity for the studied phases and structural defects: 1T-MoS2 > S vacancies > O doping >2H-MoS2. Our study has provided a new route to control the phase transition of multilayer MoS2 nanosheets with promising applications potentially in catalysis and optoelectronics.
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Materials
·
2018
·Vol. 11
·期 9
·1720
·
IF 2.467
Qiuyan Hao,Guoliang Cui,Yuan Tian,Taizhe Tan,Yongguang Zhang
In this paper, the synthesis of the three-dimensional (3D) composite of spherical reduced graphene oxide (RGO) with uniformly distributed CeO2particles is reported. This synthesis is done via a facile and large-scalable spray-drying process, and the CeO2/RGO materials are hydrothermally compounded with sulfur. The morphology, composition, structure, and electrochemical properties of the 3D S/CeO2/RGO composite are studied using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), Raman spectra and X-ray photoelectron spectroscopy (XPS), etc. The electrochemical performance of the composites as electrodes for lithium–sulfur batteries is evaluated. The S/CeO2/RGO composites deliver a high initial capacity of 1054 mAh g−1, and retain a reversible capacity of 792 mAh g−1after 200 cycles at 0.1 C. Profiting from the combined effect of CeO2and RGO, the CeO2/RGO materials effectively inhibit the dissolution of polysulfides, and the coating of spherical RGO improves the structural stability as well as conductivity.Keywords:Lithium–sulfur battery;CeO2/RGO composite;electrochemical performance
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2017
·Vol. 135
·期 16
·46187
·
IF 1.86
Xinqi Lin,Xuesong Li,Jinmeng Hao,Xuan Zhao,Yanfeng Wei,Jianxin Mu
A series of novel poly(arylene ether)s were synthesized with diphenol liner polydimethysiloxanes with different silicon numbers (2OH-PDMS- P ; P = 2, 6, 10, 12, 16) and decafluorobiphenyl via a two-step nucleophilic substitution polymerization. The chemical structures of the polymers were confirmed by Fourier transform infrared spectrometer, 19 F-NMR and 1 H-NMR spectra. All the polymers provided outstanding hydrophobic properties, high thermal stability and good solubility. The water contact angle (WCA) first increased and then suddenly decreased with the increasing of silicon numbers in PDMS. The highest WCA about 112° was obtained when silicon numbers was ten. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46187.
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