JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Jiaxing Wen,Yi Pei,Li Liu,Die Su,Min Yang,Qianfu Wang,Wen Zhang,Jing Dai,Yan Feng,Tianjing Wu,Xianyou Wang
Both antimony selenide and antimony are promising anode materials for lithium-ion batteries. However, owing to the influence of the poor electronic conductivity of Sb 2 Se 3 and the large volume expansion of the two materials during the lithiation process, their electrochemical performance is limited and the practical application is restricted. In this work, for the first time, the hierarchical Sb 2 Se 3 and Sb particles fully encapsulated into carbon nanofibers (Sb 2 Se 3 /Sb/C nanofibers) have been in-situ synthesized by electrospinning followed by controlled annealing. Combining the advantages of high specific capacity of Sb 2 Se 3 , good electronic conductivities of Sb and C, and strong stability of C matrix, the Sb 2 Se 3 /Sb/C nanofibers electrode shows excellent lithium-storage performance. It achieves a high reversible capacity (764 mA h g −1 after 300 cycles at 0.1 A g −1 ), splendid ultralong cycling stability (429 mA h g −1 after 1000 cycles at 1 A g −1 ), and high rate capability (342 mA h g −1 at 5 A g −1 ). It demonstrates that Sb 2 Se 3 /Sb/C nanofibers are promising high-performance anode materials for lithium-ion batteries.
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CONSTRUCTION AND BUILDING MATERIALS
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2020
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IF 4.419
Feng Zhang,Yin Bai,Yuebo Cai
Under low temperature environment, the concrete strength develops slowly, which will seriously hinder the construction progress. Traditional early-strength components can not meet the requirements of green and high-performance concrete, combined with the research and application of early-strength accelerators under low temperature is relatively few, and its low-temperature early-strength performance is limited, the early strength development rate of specimens is far lower than that of blank samples at 20 °C, so it is urgent to develop new early-strength component to promote the strength development rate of concrete at low temperature. In this paper, calcium bromide (CaBr 2 ) was used as an early strength component to test the 1-, 3-, 7-, and 28-d compressive strengths of the mortars and cement pastes mixed with 0–1.0% CaBr 2 under 5 °C curing. CaBr 2 had a significant effect of early strength at low temperature (5 °C), and the strength of the specimens mixed with 1.0% CaBr 2 at each age was close to or even exceeded that of the contrast samples cured at 20 °C. The equilibrium method (gravimetric method) was used to study the effect of 1 mol/L of CaBr 2 in water on the dissolution of the single ores C 3 S at different ages. CaBr 2 could promote the dissolution of C 3 S at a low temperature of 5 °C, and the solubility of C 3 S had an obvious tendency to increase. Further, X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) and energy-dispersive spectrometry (EDS) analysis and mercury infusion porosimetry (MIP) analysis were used to perform microscopic characterization (e.g., product composition, morphology, pore structure, etc.) of the hydration products of the cement single ores or mortars mixed with CaBr 2 . On this basis, the early-strength mechanism of CaBr 2 was discussed. CaBr 2 could promote the initial hydration of cement at low temperature (5 °C) and significantly increase the degree and rate of hydration of C 3 S and C 3 A single ores, and also generated new type of products, bromine-containing C–S–H gels and bromoaluminate calcium hydrate (Ca 4 Al 2 O 6 Br 2 ·10H 2 O), and the Ettringite and Ca(OH) 2 crystals were mostly formed on the surface of gel products or inside the pores. Large amounts of hydration products were generated, which refined the pore diameter of samples by reducing the most probable pore size and total porosity, thus making the microstructure of samples denser and enhancing the strength of specimens.
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Journal of Environmental Sciences
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2020
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IF 4.302
Runping Wu,Qing Ye,Kai Wu,Hongxing Dai
To improve the removal capacity of NO + O 2 effectively, the alkaline earth metal-doped order mesoporous carbon (A-C-FDU-15(0.001) (A = Mg, Ca, Sr and Ba)) and Mg-C-FDU-15( x ) ( x = 0.001−0.003) samples were prepared, and their physicochemical and NO + O 2 adsorption properties were determined by means of various techniques. The results show that the sequence in (NO + O 2 ) adsorption performance was as follows: Mg-C-FDU-15(0.001) (93.2 mg/g) > Ca-C-FDU-15(0.001) (82.2 mg/g) > Sr-C-FDU-15(0.001) (76.1 mg/g) > Ba-C-FDU-15(0.001) (72.9 mg/g) > C-FDU-15 (67.1 mg/g). Among all of the A-C-FDU-15(0.001) samples, Mg-C-FDU-15(0.001) possessed the highest (NO + O 2 ) adsorption capacity (106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O 2 on the A-C-FDU-15( x ) samples, and (NO + O 2 ) adsorption on the samples was mainly chemical adsorption. Combined with the results of (NO + O 2 )-temperature-programmed desorption ((NO + O 2 )-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, we deduced that there were two main pathways of (NO + O 2 ) adsorption: one was first the conversion of NO and O 2 to NO 2 and then part of NO 2 was converted to NO 2 − and NO 3 − ; and the other was the direct oxidation of NO to NO 2 − and NO 3 − .
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PubMed
高影响因子
TETRAHEDRON LETTERS
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2020
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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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ACS Sustainable Chemistry & Engineering
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2020
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IF 7.632
Zhiyan He,Guangxing Yang,Hongjuan Wang,Fengying Dai,Feng Peng,Hao Yu
Metal- and nitrogen-doped carbon materials (Me–N–C) have received intensive scientific interest as single-atom catalysts (SACs) for electro- and thermocatalytic reactions. In this work, the potential of Me–N–C (Me = Co, Fe, Ni)-wrapped carbon nanotubes (CNTs) as support of platinum nanoparticles (Pt NPs) for base-free oxidation of glycerol was investigated. Co-doping of transition metal and nitrogen significantly enhanced the dispersion of Pt, indicating the advantages of the supporting material for noble-metal catalysts. Two-fold improvement of turnover of glycerol was observed over 5Pt/CoNC@CNT compared to 5Pt/CNT under the same reaction conditions. A kinetics study was conducted to understand the role of CoNC as a support of Pt NPs in a wide range of oxygen partial pressure from 0.04 to 0.4 MPa and a range of glycerol concentration from 0.012 to 0.15 wt %. A synergistic effect between Me–N–C, especially Co–N–C, and Pt NPs was revealed. The Co–N–C support facilitated the activation of oxygen and thus enhanced the overall turnover of glycerol oxidation, especially at high glycerol concentrations. This finding suggests a new approach to the high-performance Pt catalysts via introducing SACs as supporting materials that afford auxiliary active sites for the target reaction.
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Inorganic Chemistry Frontiers
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2020
·Vol. 7
·期 22
·4438-4444
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IF 5.958
Yakun Tang,Yang Gao,Lang Liu,Yue Zhang,Jing Xie,Xingyan Zeng
Li2FeSiO4 is a superior cathode material for lithium ion batteries (LIBs) owing to its high capacity, low cost, and superior stability. Exhilaratingly, the material also exhibits the desired electrochemical performance as the anode for LIBs in comparison with traditional carbon materials. However, the Li2FeSiO4 anode is subject to a fatal capacity degradation in long cycles, due to its low conductivity and serious particle agglomeration. With inspiration from the unique architecture based on the hybrid nanotubes consisting of active nanoparticles embedded in CNTs, a simple and efficient sol–gel method combined with subsequent calcination has been developed for the synthesis of porous Li2FeSiO4/C hybrid nanotubes. Benefiting from the intrinsic increased conductivity of the hybrid and its robust structure, as the anode for LIBs, it exhibits a high capacity (444.7 mA h g−1 at 0.2 A g−1), superior long cycling stability (161 mA h g−1 at 2 A g−1 after 3000 cycles) and an ultra-high rate capability (261.1 mA h g−1 at 1 A g−1 and 112.9 mA h g−1 at 8 A g−1). Surprisingly, the Na2FeSiO4/C hybrid nanotube also shows satisfactory application prospects as the anode for sodium ion batteries (SIBs). Such hybrids furnish attractive potential for high-performance LIB/SIB anodes, which would be a promising substitution for carbon anodes.
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ACS Catalysis
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2020
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IF 12.35
Haiyong Wang,Haosheng Xin,Chiliu Cai,Changhui Zhu,Zhongxun Xiu,Qiying Liu,Yujing Weng,Chenguang Wang,Xinghua Zhang,Shijun Liu,Zifang Peng,Longlong Ma
Keto-alcohols, which are traditionally produced from fossil resources with multisteps, are considered as important intermediates for diversified high-value-added fine chemical synthesis due to their involved carbonyl and hydroxyl groups. Herein, direct cellulose hydrogenolysis to C3-C4 keto-alcohol products (hydroxyacetone and 1(3)-hydroxy-2-butanone) was achieved over Ni-WOx/C catalysts with an W/Ni atom ratio of 1.0–5.0. The keto-alcohol yield was proposed to strongly depend on the W/Ni ratio and the catalyst annealing temperature. The highest keto-alcohol yield of 63% was obtained at the optimal balance of basic/acidic WOx species and metallic Ni. The introduction of Ni facilitated the formation of the basic W5+ sites, which enhanced the formation of basic sites at the Ni-WOx interface. The synergistic effect between the basic W5+ and acidic oxygen vacancy (Vö) could activate the target C–O/C═O bonds, promoting the isomerization of glucose and C3-C4 aldehyde intermediates with the assistance of the interfacial Ni. The cooperative adsorption of the −OH and −C═O groups at the Ni-O-W-Vö interface stabilized the adjacent ketone and hydroxyl groups and kept the other hydroxyl groups for hydrogenolysis, obtaining the final C3-C4 keto-alcohols. This work expanded the application of cellulosic biomass, enabling the green and sustainable synthesis of the high-value C3-C4 keto-alcohol products using lignocellulosic biomass as a raw material.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Lei Li,Guilin Li,Wenjun Ouyang,Yaping Zhang,Fanzhen Zeng,Chenyu Liu,Zhan Lin
The realization of balance between relative permittivity and permeability is still a great challenge in the development of microwave absorption materials. Based on the controllable MOFs precursor, bimetallic Fe/M (M = Co, Ni, Mn) doped carbon derived from pyrolyzing bimetallic MOFs (FeM-MIL-88B) exhibits intriguing microwave absorption property. By tuning the second metal source and the ratio of Fe/M, in this work we realize impedance matching between free space and the absorber. Optimized FeCo 2 @C exhibits strong EMW absorption performance (-71.4 dB) and broad bandwidth (14.2 GHz) with a low filler loading of 25 wt%. The synergistic effect of the bimetal source on carbonization process and electric/magnetic properties prove that rationally doping the second metal source into the Fe-MOFs precursor to generate bimetallic magnetic nanoparticles/C material play an intensified role to tune the microwave absorption performance.
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Natural Product Communications
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2020
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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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高影响因子
Nano Research
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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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NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 17
·6810-6817
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IF 3.288
Yanchao Xu,Shanshan Xiong,Shuting Weng,Juan Wang,Jing Wang,Hongjun Lin,Yang Jiao,Jianrong Chen
N-Doped carbon-incorporated Ni2P/Ni was reasonably designed and synthesized from nickel-based metal organic framework (Ni-MOF) precursors via a novel simultaneous carbonization and phosphatization process. Interestingly, subtle phosphating significantly improves the energy storage performance of supercapacitors (SCs). Ni2P/Ni/C composites exhibit a good energy storage performance with a specific capacitance of 257.2 C g−1 at 1 A g−1. The corresponding hybrid supercapacitor achieves an energy density of 25.4 W h kg−1 at a power density of 750 W kg−1, ultrahigh electrochemical cyclic stability (98.2% retention after 4000 cycles) and nearly 100% coulombic efficiency with a Ni2P/Ni/C-100 positive electrode and a porous carbon negative electrode, respectively. These can be attributed to the synergetic effects of N-doped carbon and metal phosphates, which ensure good electrical conductivity and provide rich reactive sites as well as stable architecture. These results indicate that the controlled pyrolysis of MOFs is an effective method to design a kind of high-performance electrode material for hybrid supercapacitors.
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ChemElectroChem
·
2020
·Vol. 7
·期 7
·1775-1780
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IF 4.154
Xinyue Zhang,Qingtao Liu,Jianglan Shui
Graphical Balancing act : Polytetrafluoroethylene (PTFE) is added to different positions of the Fe−N−C catalyst layer by using three methods to adjust its hydrophobicity. An appropriate amount of PTFE in the Fe−N−C catalyst layer is beneficial to the power density of the PEM fuel cell. However, the hydrophobicity of the Fe−N−C catalyst layer does not affect the long-term durability of the fuel cells, although high hydrophobicity will improve the fuel cell initial durability. The hydrophobicity of the cathode catalyst layer (CCL) affects the performance of the proton exchange membrane fuel cell (PEMFC) by adjusting the water management of the catalyst layer, which has been extensively studied in Pt-based catalysts. Here, the effect of the hydrophobicity of Fe−N−C CCL on the performance of the PEMFC is investigated. The hydrophobicity of the Fe−N−C CCL is tuned by polytetrafluoroethylene (PTFE) by using three addition methods: 1) coat PTFE on Fe−N−C powder and heat-treat; 2) mix PTFE emulsion with Fe−N−C ink and then brush the electrode; and 3) transfer a ground PTFE/Fe−N−C composite film onto the gas diffusion layer by the decal method. For each PTFE addition method, the optimized PTFE amount can increase the power density of Fe−C−N PEMFC by 15.1 %, 26.6 %, and 87.2 %, respectively. At the same time, it is found that enhanced hydrophobicity reduces the initial current decay rate of the Fe−N−C CCLs, but their residual current densities are close after a 50 h durability test at 0.5 V in a H 2 -O 2 PEMFC. It can be concluded that the hydrophobicity of the Fe−N−C CLL has a great influence on the power density of the fuel cell, but the influence on the long-term durability of the fuel cell is negligible.
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