Catalysts
·
2019
·Vol. 9
·期 6
·538
·
IF 3.444
Lili Liu,Xiaojing Zhou,Li Liu,Shuai Jiang,Yingjie Li,Luxia Guo,Shijuan Yan,Xishi Tai
Three bimetallic Cu–Ni nanoparticle-supported catalysts were synthesized by co-immobilization followed by H2reduction. A chromium(III) terephthalate metal organic framework (MIL-101), titanium dioxide (TiO2), and carbon (C) with different properties (acidity and Brunauer–Emmett–Teller surface area) were selected as supports for studying the effect of the support nature on the catalytic activity and selectivity in the oxidation of benzyl alcohol. The physicochemical properties of the Cu–Ni-supported catalysts were characterized by XRD, NH3-TPD, nitrogen adsorption/desorption, TEM, EDS, XPS, and ICP-OES. Bimetallic Cu–Ni nanoparticles were highly dispersed on the support. The catalytic activities of CuNi/MIL-101, CuNi/TiO2, and CuNi/C were tested in the selective oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen under mild reaction conditions. The highest benzaldehyde yields were achieved with CuNi/TiO2, CuNi/MIL-101, and CuNi/C catalysts at 100 °C within 4 h under 5, 3, and 3 bar of O2, respectively. The bimetallic Cu–Ni-supported catalysts possessed two types of catalytic active sites: acid sites and bimetallic Cu–Ni nanoparticles. The CuNi/MIL-101 catalyst possessed a high number of acid sites and exhibited high yield during selective benzyl alcohol oxidation to benzaldehyde. Importantly, the catalysts exhibited a high functional group (electron-donating and electron-withdrawing groups) tolerance. Cu–Ni-supported catalysts with an Cu:Ni mole ratio of 1:1 exhibited the highest yield of 47% for the selective oxidation of benzyl alcohol to benzaldehyde. Reusability and leaching experiment results exhibited that CuNi/MIL-101 showed better stability than CuNi/TiO2and CuNi/C catalysts due to the large porous cavities of MIL-101 support; these cavities can be used to trap bimetallic Cu–Ni nanoparticles and inhibit nanoparticle leaching.Keywords:Cu–Ni nanoparticles;MIL-101;TiO2;carbon;benzyl alcohol oxidation
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高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Guodong Du,Yakun Xi,Xiaohui Tian,Yanbin Zhu,Yingke Zhou,Chengji Deng,Hongxi Zhu,Angulakshmi Natarajan
Three-dimensional (3D) porous LiFePO 4 /graphene aerogel (LFP/GA) composite was successfully prepared by an in-situ hydrothermal process. In this composite, the LiFePO 4 microspheres assembled by nanoparticles were embedded in a three-dimensional framework intertwined with the graphene sheets, which acts as a bridge for transfer of electron and diffusion of lithium ion . The large specific surface of the composite structure enables the increased infiltration area and utilization of the active material. The content of the graphene sheet is analyzed and is found important for the Li-storage characteristics of LiFePO 4 . An aerogel composite with 10% of graphene displays the best electrochemical performance, with the specific discharge capacities of 168 mAh g −1 and 155 mAh g −1 at respectively 0.1C and 1C, and the capacity retains 96.3% for up to 800 cycles. This novel 3D porous aerogel composite is identified as a promising cathode material for the rechargeable Li battery, and the simple strategy may be applied to construct other high performing composite structure and materials.
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高影响因子
ChemElectroChem
·
2019
·Vol. 6
·期 11
·2883-2890
·
IF 3.975
Fangfang Zhu,Jiuqing Liu,Haijun Zhao,Jie Li,Qihou Li,Yang Xi,Meng Liu,Cheng Wang
Graphical Better apart : A porous polyetherimide (PEI)/Al 2 O 3 separator for lithium-sulfur batteries is prepared through non-solvent-induced phase separation. PEI/Al 2 O 3 has a dense structure on one side and the other side offers a loose and porous structure. This special morphology has a physical blocking effect on polysulfides. Also, the PEI/Al 2 O 3 separator possesses excellent thermal stability and ionic conductivity of practical significance. The assembled cell with the prepared PEI/Al 2 O 3 separator exhibits a better cycling performance than that with the commercial Celgard 2320 separator. As an important component of lithium-sulfur batteries, the separator has a critical role in battery safety and the corresponding electrochemical performance. In this study, a high-performance polyetherimide (PEI)/Al 2 O 3 separator was prepared through the non-solvent-induced phase separation (NIPS) technique. It was demonstrated that the existence of Al 2 O 3 affects the morphology, thermal stability, electrolyte uptake, ionic conductivity, and electrochemical properties of the PEI/Al 2 O 3 separator. The results indicate that PEI/Al 2 O 3 separators containing 5 and 6 wt % Al 2 O 3 possess high porosity, good electrolyte uptake, excellent thermal stability (thermal shrinkage ratio is only 0.78 % even at a high temperature of 200 °C), and ionic conductivity of practical significance (up to 2.20 mS ⋅ cm −1 ). Consequently, the assembled cell with the prepared PEI/Al 2 O 3 separator exhibits a better cycling performance (724.9 mA h g −1 after 200 cycles at 0.2 C) than that with the commercial Celgard 2320 separator. Therefore, the PEI/Al 2 O 3 separator prepared by NIPS is a potential separator candidate for high-safety and high-performance dischargeable lithium-sulfur batteries.
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NEUROGASTROENTEROLOGY AND MOTILITY
·
2019
·Vol. 31
·期 6
·e13555
·
IF 3.803
Mengjuan Lin,Lei Chen,Yong Xiao,Baoping Yu
Background Irritable bowel syndrome (IBS) is a common disease with intestinal dysmotility, whose mechanism remains elusive. The endocannabinoid system is emerging as an important modulator of gastrointestinal (GI) motility in multiple diseases, but its involvement in IBS is unknown. We aimed to determine whether cannabinoid 2 (CB2) receptor modulates intestinal motility associated with stress-induced IBS. Methods A rat IBS model was established by chronic water avoidance stress (WAS). Colonic pathological alterations were detected histologically and intestinal motility was assessed by intestinal transit time (ITT) and fecal water content (FWC). Visceral sensitivity was determined by visceromotor response (VMR) to colorectal distension (CRD). Real-time PCR, western blot, and immunostaining were performed to identify colonic CB2 receptor expression. Colonic muscle strip contractility was studied by isometric transducers and nitric oxide (NO) was detected by the Griess test. The effects of AM1241, a selective agonist of CB2 receptors, on colonic motility were examined. Key Results After 10 days of WAS exposure, ITT was decreased and FWC elevated while VMR magnitude in response to CRD was significantly enhanced. Colon CB2 protein and mRNA levels increased and density of CB2-positive macrophages in the mucosa and enteric neurons in the myenteric plexus was higher than in controls. Pharmacological enhancement of CB2 activity by AM1241 relieved colonic hypermotility in WAS rats in a concentration-dependent manner via inhibition of p38 phosphorylation and elevation of NO production. Conclusion CB2 receptor may exert an important inhibitory effect in stress-induced colonic hypermotility by modulating NO synthesis through p38 mitogen-activated protein kinase signaling. AM1241 could be used as a potential drug to treat disorders with colonic hypermotility.
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PubMed
高影响因子
KEY ENGINEERING MATERIALS
·
2019
·
IF 0
Yan Kai Huang,Qi Lin Mei,Zhi Xiong Huang,Yan Qin,Di Zhu
In this paper, the structure of the photosensitive diamines was designed and the method of synthesizing such diamines was investigated. The 1-(3-aminophenyl)-3-(4-aminophenyl)-2-propen-1-one analyzed by elemental analysis and infrared analysis was synthesized through two-step experiments with Aldol condensation and Nitroammoniation process. Through the experiment the optimum reaction conditions are raw material ratio of 1:1, anhydrous ethanol dosage of 60 ml, 10 % NaOH dosage of 10 ml and reaction temperature of 25°C for 4h. The yield was about 55.4 %.
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ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Xinlu Li,Yin Liu,Xinlin Zhang,Cong Yao,Ronghua Wang,Chaohe Xu,Juan Lei
A porous spherical hybrid of TiO 2 (B)/anatase entwined by graphene nanoribbons (GNRs) was synthesized by a facile and scalable method. The entwining of GNRs can adhere on the surface of TiO 2 by electrostatic interactions and prevent TiO 2 nanoribbons from self-scrolling to nanotubes , facilitating large lithium storage and high rate capability. The TiO 2 /GNRs nanocomposite exhibited high rate capability in galvanostatic charge-discharge experiments, providing a capacity of 131 mAh g −1 with a coulombic efficiency of 99.2% at a charge rate of 10C (1 C = 335 mA g −1 ) over 1400 cycles. The appealing electrochemical performance can be attributed to the synergistic effect of TiO 2 nanoribbons entwined by GNRs.
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RSC Advances
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2018
·Vol. 8
·期 69
·39742-39748
·
IF 2.936
Jinfeng Yan,Yanan Ma,Chuankun Zhang,Xingxing Li,Weizhi Liu,Xinyu Yao,Shuai Yao,Shijun Luo
Recently, more and more researchers have devoted their efforts to developing flexible electrochemical energy storage devices to meet the development of portable and wearable electronics. Among them, supercapacitors (SCs) have been widely studied due to their high specific capacitance and power density. However, most flexible SCs often use traditional carbon materials and transition metal oxides as electrode materials. In this paper, we used an easy and low-cost way to fabricate a flexible supercapacitor based on a new type of two-dimensional material, transition metal carbides, nitrides, or carbonitrides (MXenes). By taking full advantage of the hydrophilicity and metal conductivity of MXene nanosheets, an extremely simple “dipping and drying” method was used to achieve conductive textile electrodes with a specific capacitance of 182.70 F g−1, which is higher than reported for carbon nanotubes (CNTs) and active carbon. To further improve the capacitive performance of the MXene-based electrode and avoid the poor oxygen oxidation of MXene, polypyrrole (PPy) was electrochemically deposited on the surface of MXene textiles, thus producing a PPy–MXene coated textile electrode with a specific capacitance of 343.20 F g−1. In addition, a symmetrical solid-state supercapacitor based on MXene–PPy textiles was assembled, which achieved an energy density of 1.30 mW h g−1 (power density = 41.1 mW g−1). This work introduces a new type of MXene-based textile SC, which provides a promising candidate for flexible and wearable energy storage devices.
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PubMed
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2019
·Vol. 34
·期 14
·2445-2455
·
IF 1.982
Uwamahoro Evariste,Guohua Jiang,Bo Yu,Yongkun Liu,Zheng Huang,Qiuling Lu,Pianpian Ma
In this work, hierarchical mesoporous Zn–Ni–Co–S–rGO/NF microspheres have been prepared by hydrothermal, sulfurization, and subsequent calcination process. The effect of different sulfurization time on the morphology and capacitance of composites was tested. The high electrochemical performance of (Zn–Ni–Co–S–rGO/NF) composite was obtained when the sulfurization time was 3 h (Zn–Ni–Co–S–rGO/NF-3h), where a specific capacitance of 627.7 F/g at 0.25 A/g and excellent rate capability of about 97.8% capacitance retention at 2 A/g after 4000 cycles were achieved. Moreover, an asymmetric supercapacitor fabricated by (Zn–Ni–Co–S–rGO/NF-3h) composite and activated carbon (AC) as the positive and the negative electrodes, respectively, showed a high energy density of 75.96 W h/kg at a power density of 362.49 W/kg with a remarkable cycle stability performance of 91.2% capacitance retention over 5000 cycles. This incredible electrochemical behavior illustrates that the hierarchical mesoporous Zn–Ni–Co–S–rGO/N-3h microsphere electrodes are promising electrode materials for application in high-performance supercapacitors.
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高影响因子
CARBON
·
2019
·
IF 7.466
Shang-Fa Pan,Jiang-Long Yin,Xue-Lian Zhu,Xiao-Jing Guo,Ping Hu,Xi Yan,Wan-Zhong Lang,Ya-Jun Guo
In this work, a variety of microporous carbon nanospheres (MCNs) were synthesized by the in-situ approach, and used as metal-free catalysts for direct propane dehydrogenation (DPDH). Pristine MCNs showed excellent catalytic performances for DPDH with initial propane conversion of 26% and propylene selectivity of 87%–88%. Phosphorus (P) modifications with different P sources put different effects on the catalytic performances of MCNs in DPDH, i.e., triethyl phosphate exhibited a positive, while (NH 4 ) 2 HPO 4 and H 3 PO 4 showed a negative effect on the catalytic performances for the in-situ doping carbon catalysts. The amount of surface oxygenic groups and the graphitization extent of carbon materials are two important factors influencing the catalytic performances of MCNs in DPDH. These results indicate that P modification is an effective way to adjust the catalytic performances of MCNs in DPDH. While, except the dopant itself, the interaction between the dopant and other materials during the synthesis process also influences the surface oxygenic groups and the graphitization degree of carbon materials.
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高影响因子
JOURNAL OF POWER SOURCES
·
2019
·
IF 7.467
Qin Li,Yanli Li,Jing Zhao,Shihang Zhao,Jiaojiao Zhou,Chen Chen,Kai Tao,Rui Liu,Lei Han
The rational control of metal-organic frameworks derived hollow nanomaterials with rapid mass transport and multiple active metal sites are desirable for emerging energy storage. Herein, CoMoO 4 hollow microplate array on Ni foam is prepared via a facile self-sacrificing templated strategy from ion-exchange of cobalt-organic framework microplate array. Benefiting from hollow microplate structure constructed by ultrathin nanosheets , CoMoO 4 as binder-free electrode for supercapacitor delivers ultrahigh areal capacitance/capacity (12.2 F cm −2 /6120 C cm −2 at 2 mA cm −2 ), superior rate property (82.2% at high current density of 50 mA cm −2 ) and excellent cycling stability (90.5% retention after 5000 cycles). Moreover, an asymmetric supercapacitor device is assembled by using CoMoO 4 as positive electrode and activated carbon as negative electrode , achieving high energy density of 0.321 mWh cm −2 at power density of 1.7 mW cm −2 and superior capacitance retention of 96.0% over 5000 cycles. Importantly, a blue light-emitting diode can be illuminated 2 min, indicating a great potential for practical applications. These excellent results demonstrate that this efficient strategy can extend to prepare various bimetallic oxides arrays with hollow and hierarchical microstructure for high-performance supercapacitors .
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IONICS
·
2019
·Vol. 25
·期 7
·3107-3119
·
IF 2.289
Lu Qinghua,Zhu Qinglin,Guo Weimin,Li Xiaoman
Lithium–sulfur (Li–S) battery is one of the most promising next-generation energy storage devices due to its high-capacity density and low cost. However, lithium–sulfur batteries could not be widely used in a large range due to the “shuttle effect” and sulfur insulation. Herein, we proposed a novel composite cathode of carbon nanotubes@manganese dioxide@sulfur@polypyrrole (C@MnO 2 @S@PPy). X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM) BET analysis show that sulfur filled into the pores of C@MnO 2 , and PPy was successfully coated on C@MnO 2 @S. TG indicated that the compound contained 60 wt% active sulfur. The prepared cathode of C@MnO 2 @S@PPy composites shows excellent rate performance and cycle stability. At a high rate of 1C, its maximum discharge capacity reached 1218 mA h g-1 and its average capacity decreasing rate was only 0.096%/cycle when running over 500 cycles. The interaction mechanism of MnO 2 with polysulfides was investigated by adsorption tests and XPS analysis. The excellent electrochemical performance might be due to a combination of adsorption or catalytic properties of MnO 2 and the conductivity of carbon materials and PPy.
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ACS Omega
·
2019
·
IF 2.584
Chen Liang,Yan Wang,Yangdong Hu,Lianying Wu,Weitao Zhang
Butyl levulinate (BL) is a versatile chemical utilized widely in food and chemical industries, the production of which by using cellulose in biomass resources is of great significance to its sustainable development. Traditional synthesis processes for n-butyl levulinate are confronted with various problems such as high cost of raw materials, difficulty in separating products, etc. In this paper, a novel process for the preparation of BL from cellulose is proposed. The process is composed of five main unit operations including fed-batch hydrolysis, decolorization, extraction, esterification and purification. A 171.63 g/L concentration of the intermediate levulinic acid was obtained at the fifth feeding through the fed-batch hydrolysis process. The resin-activated carbon secondary decolorization method was adopted to remove the soluble humin byproducts with an accumulative decolorization rate of 89%. In the extraction process, the product BL was chosen as the extractant to avoid the introduction of new impurities. After purification, the purity of the final product BL reaches up to 98 wt %. The proposed technique allows for cost-effective and eco-friendly production of BL from biomass resources.
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