ChemElectroChem
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2016
·Vol. 3
·期 7
·1116-1123
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IF 3.506
Ji Liu,Ligui Li,Wenhan Niu,Nan Wang,Dengke Zhao,Shuaibo Zeng,Shaowei Chen
Graphical A new role for the HOF : A hydrogen-bonded organic framework (HOF) comprising of melamine and trimesic acid is used as a highly porous precursor to prepare N-doped carbons by a facile, direct pyrolysis. The resulting mesoporous carbon HOF-800 has a high surface area of 1321 m 2 g −1 and efficiently catalyzes oxygen electroreduction in alkaline electrolyte. Direct carbonization methods represent a facile strategy for the synthesis of functional carbon electrocatalysts, however, the resulting carbons are mostly microporous and of low surface area, which disfavor mass transfer, and usually have low electrocatalytic activity. In this study, a hydrogen-bonded organic framework (HOF) comprising of melamine and trimesic acid is used as a highly porous precursor to prepare N-doped carbons through facile, direct pyrolysis. The high nitrogen content of melamine and the intrinsically porous nature of the HOF facilitates the formation of a mesoporous carbon with 4.8 atom % content of nitrogen dopants and a significantly high surface area of 1321 m 2 g −1 . Electrochemical measurements show that the best sample, which was pyrolyzed at 800 °C (HOF-800), exhibited efficient catalytic activity for oxygen electroreduction in 0.1 m KOH aqueous solution. This catalyst exhibits a much more positive onset potential, higher diffusion-limited current density, higher electron-transfer number in the low overpotential region, higher stability, and stronger tolerance against methanol crossover than the state-of-the-art Pt/C catalysts. The results in this study suggest the potential of intrinsically porous HOFs for the development of highly efficient nonprecious-metal electrocatalysts.
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CHEMOSPHERE
·
2016
·
IF 3.698
Ying Han,Zhong-lin Chen,Ji-min Shen,Ji-he Wang,Wei-wei Li,Jun Li,Bin-yuan Wang,Li-na Tong
The role of Cu(II) in the reduction of N -nitrosodimethylamine (NDMA) with zero-valent metals was investigated by determining the effects of Cu(II) on the removal, kinetics, products, and mechanism. NDMA removal was enhanced, and all reactions followed a pseudo-first-order kinetic model except for the Fe and Fe/0.1 mM Cu(II) systems. The iron mass-normalized pseudo-first-order rate constants ( k MFe ) increased with the Cu(II) concentration. The zinc mass-normalized pseudo-first-order rate constants ( k MZn ) were identical to those with the Cu(II) concentrations from 0.1 mM to 1.0 mM and were higher with 2.0 mM Cu(II). The types of products detected were unchanged. Some unknown products were also found. NDMA was reduced to 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine , UDMH). Then, UDMH was reduced into dimethylamine (DMA) by the Fe/Cu(II) and Zn/Cu(II) systems. Catalytic hydrogenation was proposed as the reduction mechanism. Several copper species, such as Cu(OH) 2 in the Fe/Cu(II) system and Cu 2 O and Cu(OH) 2 in the Zn/Cu(II) system enhanced NDMA reduction. Differences between the Fe/Cu(II) and Zn/Cu(II) systems were caused by the reduction potentials and surface conditions of the different metals and the copper species in the various systems.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2016
·
IF 3.014
Zhiwei Zhang,Hanning Li,Jie Hu,Baozhong Liu,Qingrui Zhang,Carlos Fernandez,Qiuming Peng
A novel nitrogen-doped biomass carbon/silver (C-N/Ag) composite has been synthesized by a simple method, wherein the precursor of soymilk simultaneously serves as carbon and nitrogen sources, reductant and substrate. The structure, morphology and valence state of samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectra. Results show the formation of nano-sized Ag homogenously disperses on the surface of mesoporous substrate, and the self-reduction role mainly attributes to the presence of unsaturated carbon bonding. Electrochemical properties were characterized by galvanostatic discharge and impedance spectra techniques. The sample prepared with 1 mmol AgNO 3 solution, activated by 0.1 M KOH and annealed at 900 °C shows excellent oxygen reduction reaction activity and good electrochemical durability in alkaline medium. The onset potential, limiting diffusion current density and electron transfer number are 0.93 V, 6.26 mA cm −2 and 4.00, respectively, superior to those of 60 wt.% Ag/C and comparable to 20 wt.% Pt/C catalysts correspondingly. The discharge performance of Zn-air batteries is better than that of 20 wt% Pt/C.
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RSC Advances
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2016
·Vol. 6
·期 45
·38957-38963
·
IF 3.289
Zhao Cui,Ru Cheng,Jie Liu,Youping Wu,Jianping Deng
Poly(N-acryloyl-alanine)-based hydrophobic association hydrogels were prepared through free radical polymerization of N-acryloyl-alanine (NAA) with ammonium persulfate as initiator, in which hydrophobic monomer stearyl acrylate underwent simultaneous micellar polymerization in the presence of gelatin as emulsifier. Fourier transform infrared spectra and scanning electron microscopy demonstrated the formation and microscopic structure of the resulting hydrogels. The hydrophobic association enabled the hydrogels to exhibit desirable toughness and could be molded into diverse shapes without breaking. Uniaxial tensile test and cyclic tensile test also demonstrated the high toughness of the hydrogels. The chiral monomer (NAA)-derived polymer chains rendered the hydrogels with optical activity, according to circular dichroism spectra. More fascinatingly, the hydrogels demonstrated shape memory behavior due to the hydrophobic poly(stearyl acrylate) domains. Therefore the tough chiral hydrogels are expected to find significant applications in tissue engineering and other biomedical fields.
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APPLIED CATALYSIS A-GENERAL
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2016
·
IF 4.012
Hezhan Jiang,Xiaolong Yu,Renfeng Nie,Xinhuan Lu,Dan Zhou,Qinghua Xia
Mesoporous carbon nitride (MCN) has been prepared through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach. The obtained MCN possesses high surface area (166.3 m 2 /g), average pore size of 9.2 nm and high N content (up to 18.5 wt%). The negative charge and the basicity on MCN surface are originated from its rich carbon nitride heterocycles, which notably improves the surface hydrophilicity and the adsorption of acidic molecules. Furthermore, MCN can be adopted as the proper support for highly dispersed Pd NPs with well-controlled size distribution. Compared with microporous N-doped active carbon with low N-content, the MCN-supported Pd catalyst shows an enhanced activity in water phase for the selective ring hydrogenation of benzoic acid, benzamide and phenol, in which 11.3 times higher activity in comparison to undoped catalyst is achieved. Wide characterizations reveal that big pore size, selective adsorption for acid substrate and strong interaction between N and Pd may lead to the high activity of Pd/MCN.
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COMPOSITES COMMUNICATIONS
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2017
·
IF 0
Ying Bai,Xue Mao,Jun Song,Xia Yin,Jianyong Yu,Bin Ding
Study of high-efficiency and free secondary pollution TiO 2 based photocatalyst has become the one of the most urgent problems in improving the decolorization effect of the waste water from printing and dyeing mill. In this work, a novel self-standing Ag 2 O@YSZ-TiO 2 p-n nanoheterojunction nanofibrous membrane was designed for ultraviolet (UV) photocatalyst by a facile combination of electrospinning technique and precipitation process. Moreover, the UV photocatalytic performance of the flexible AZT p-n nanoheterojuction nanofibrous membranes with a band gap energy of 2.89 eV and good reversibility of 5 cycles, was superior to the commercial catalyst P25 for photocatalytic degradation of methylene blue. Furthermore, the photocatalytic mechanism of the flexible Ag 2 O@YSZ-TiO 2 nanofibrous photocatalyst was proposed by the electron transition in Ag 2 O/TiO 2 p-n nanoheterojunction, which showed a new insight to development of flexible and high-efficiency nanoheterojunction nanocrystalline photocatalytic membranes.
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PLoS One
·
2017
·Vol. 12
·期 5
·e0178213
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IF 2.806
Yangyang Wang,Fangfang Li,Xinling Ruan,Jian Song,Lv Lv,Liyuan Chai,Zhihui Yang,Lin Luo
A stable bacterial consortium (LV-1) capable of degrading di- n -butyl phthalate (DBP) was enriched from river sludge. Community analysis revealed that the main families of LV-1 are Brucellaceae (62.78%) and Sinobacteraceae (14.83%), and the main genera of LV-1 are Brucella spp. (62.78%) and Sinobacter spp. (14.83%). The optimal pH and temperature for LV-1 to degrade DBP were pH 6.0 and 30°C, respectively. Inoculum size influenced the degradation ratio when the incubation time was < 24 h. The initial concentration of DBP also influenced the degradation rates of DBP by LV-1, and the degradation rates ranged from 69.0–775.0 mg/l/d in the first 24 h. Degradation of DBP was best fitted by first-order kinetics when the initial concentration was < 300 mg/l. In addition, Cd 2+ , Cr 6+ , and Zn 2+ inhibited DBP degradation by LV-1 at all considered concentrations, but low concentrations of Pb 2+ , Cu 2+ , and Mn 2+ enhanced DBP degradation. The main intermediates (mono-ethyl phthalate [MEP], mono-butyl phthalate [MBP], and phthalic acid [PA]) were identified in the DBP degradation process, thus a new biochemical pathway of DBP degradation is proposed. Furthermore, LV-1 also degraded other phthalates with shorter ester chains (DMP, DEP, and PA).
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APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Junxia Guo,Qijian Niu,Yichun Yuan,Inamullh Maitlo,Jun Nie,Guiping Ma
One-dimensional (1D) nanomaterials have gained attention in energy conversion, storage, and catalyst due to the unique physical and chemical properties. Electrospinning is a kind of simple, versatile, and cost-effective technology to fabricate 1D functional nanofibers. Herein, electrospun polyacrylonitrile (PAN), melamine, and ferric chloride hexahydrate (FeCl 3 ·6H 2 O) composite nanofibers are used as template, and polythiophene (PT) are prepared by photopolymerization technology on the surface of electrospun nanofibers as shell part of fibers. Then, the core–shell nanofibers are pyrolyzed and converted into Fe–S/N–C nanofibers, which can be used as catalysts for ORR due to the metal and S-/N-codoped structure and unique 1D structure which provided facile pathways for efficient mass transport and charge transfer. The ORR electrocatalytic ability of Fe–S/N–C nanofibers is tested and present excellent property, especially in stability and methanol crossover. The electrocatalytic ability of sample is comparable to that of 20 wt% Pt/C benchmarks. These results offer an easy pathway for exploring metal-heteroatom-codoped carbon nanofibers applicable for ORR catalyst.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2017
·Vol. 33
·期 1
·70-73
·
IF 1.024
Li Bochao,Lin Xinrui,Zhang Yumin,Zhang Dawei,Xiao Yang,Lin Feng
A new series of 1-substituted phenyl-2-(1 H -1,2,4-triazol-1-yl)ethanone derivatives 3 a― 3 f was synthe-sized and their structures were characterized by IR, 1 H NMR, 13 C NMR and HRMS spectral analysis. Antimicrobial activities of the derivatives were measured against both bacteria and fungi. In vitro antifungal evaluation showed that five compounds( 3 b― 3 f) had growth inhibitory effects on the tested fungus, and three of them( 3 b, 3 c and 3 e) showed special efficacy against Gram negative bacteria.
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Journal of Energy Chemistry
·
2016
·
IF 2.322
Ran An,Guizhuan Xu,Chun Chang,Jing Bai,Shuqi Fang
Butyl levulinate (BL) is a promising new candidate as diesel fuel and fuel additive. In this study, an efficient process for a one-pot synthesis of BL from biomass-derived carbohydrates in butanol medium with the catalysis of metal sulfates was developed. The catalytic activity of a series of metal sulfates for the synthesis of BL from fructose was investigated. Among various metal sulfates, ferric sulfate Fe 2 (SO 4 ) 3 was found to be the most efficient catalyst, which gave a remarkably high BL yield of 62.8 mol% under the conditions of 463 K, 3 h, a catalyst dosage of 5.0 g/L, and fructose concentration of 25 g/L. Different carbohydrates including glucose, cellulose , inulin and sucrose were also used for one-pot synthesis of BL with the catalysis of Fe 2 (SO 4 ) 3 , showing the yields of 39.6, 30.5, 56.6 and 50.1 mol%, respectively. In addition, the recycling and reuse of Fe 2 (SO 4 ) 3 was studied by characterizing them using powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS). A plausible reaction pathway for the one-pot synthesis of BL from fructose was proposed. This study provides a facile and feasible way for the synthesis of BL from biomass.
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RSC Advances
·
2016
·Vol. 6
·期 79
·75626-75631
·
IF 3.289
Jinbao Liu,Yilin Liu,Yani Ai,Hongyan Chen,Chenqi Feng,Ningbo Yu,Ning Fu,Sheng Han,Hualin Lin
Two-dimensional MoS2 nanoplates within N-doped carbon from polyaniline (PANI) were fabricated by a simple hydrothermal method. During this process, PANI facilitated the absorption of inorganic precursors and provided confined spaces for the growth of MoS3 nanoparticles in the case of the unwanted aggregations. The unique nanostructure and composition of the nanoplates achieved high capacity. When CNFs@NC/MoS2 was used as an anode in lithium-ion batteries, it maintained an ultrahigh capacity of 900.9 mA h g−1 at a current density of 200 mA g−1 for 80 cycles. Even when the current density returned to 100 mA g−1 after cycling at different rates, a capacity of 998 mA h g−1 was still achieved.
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INTERNATIONAL JOURNAL OF MINERAL PROCESSING
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2017
·
IF 1.561
Cheng Zhang,Cheng Liu,Qiming Feng,Yanfei Chen
Utilization of N -carboxymethyl chitosan (N-CMCh) to limit the detrimental effect of serpentine on the flotation of pyrite is presented in this work. Flotation results show that the presence of hydrophilic serpentine slimes results in lower recoveries of the valuable pyrite. Utilization of N -carboxymethyl chitosan can limit the detrimental effect of serpentine on the flotation of pyrite. Zeta potential measurements illustrate that N-CMCh is with negative charge and the electrostatic interaction between serpentine and N-CMCh is occurred at pH 8.5, then the serpentine zeta potential will be changed from positive to negative, the electro-steric attraction converts into electro-steric repulsion between pyrite and serpentine and the pyrite recovery is improved.
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