ChemCatChem
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2018
·Vol. 10
·期 18
·4010-4017
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IF 4.674
Kui Ma,Zhonghui Cui,Zhitao Zhang,Jingjing Huang,Zhirui Sun,Ye Tian,Tong Ding,Xingang Li
Graphical Blowing off steam : This paper describes a new approach of designing Cu−Ni bimetallic catalytic systems for dimethyl ether/methanol steam reforming. The Cu−Ni system exhibits an interesting alloy-mediated selectivity of CO and CH 4 , thereby producing hydrogen-rich reformates with an ultra-low CO concentration (<1000 ppm), which could be commercially potential for fuel cells. Steam reforming of simple oxygenated hydrocarbons without C−C bonds is suitable for small-scale decentralized H 2 production for fuel cells. However, the relatively high CO concentration in H 2 -rich reformates produced by traditional Cu-based catalysts will poison the Pt-based anode in fuel cells. Here, we describe a new approach to the design of Cu−Ni bimetallic catalysts based on nickel-phyllosilicate for steam reforming of dimethyl ether (DME). With the tunable formation of the Cu−Ni alloy, we can modulate the selectivity of CO and CH 4 in steam reforming and achieve H 2 -rich reformates with an ultra-low concentration of CO (below 1000 ppm). This process only requires simple and low-energy purification pretreatments to meet the requirements of commercial fuel cells. Mechanistic studies reveal that the Cu−Ni alloy can adsorb CO, particularly at high temperatures, and simultaneously suppress CO dissociation to methane.
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FUEL PROCESSING TECHNOLOGY
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2018
·
IF 3.956
Qilei Yang,Ang Cao,Na Kang,Kang An,Zhao-Tie Liu,Yuan Liu
The catalyst for direct ethanol synthesis (DES) from syngas was investigated in this work, which is Co/La 2 O 3 -doped La 4 Ga 2 O 9 . The catalyst was prepared by using LaCo 1−x Ga x O 3 with perovskite phase as the precursor to intensify the interaction in the elements of Co, La and Ga. The catalysts were characterized by using XRD , H 2 -TPR, TEM , EDS, XPS , BET, ICP and TG techniques. This catalyst showed high selectivity to ethanol and excellent stability including excellent resistance to sintering and carbon deposition . It seems that the ethanol is generated in the interface between metallic Co and La 4 Ga 2 O 9 , and in the interface cobalt would be positively charged due to the interaction between Co nanoparticles and La 4 Ga 2 O 9 . The results and the related discussions indicate that Co/La 2 O 3 -doped La 4 Ga 2 O 9 catalyst is a promising catalyst for DES from syngas. Graphical abstracts.
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JOURNAL OF CATALYSIS
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2018
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IF 6.759
Huihuang Fang,Alberto Roldan,Chenchen Tian,Yanping Zheng,Xinping Duan,Kun Chen,Linmin Ye,Stefano Leoni,Youzhu Yuan
Tungsten carbides exhibit excellent performance in many heterogeneous processes because of their distinctive catalytic properties. Preparation of tungsten carbides with controllable phase composition relevant to their catalytic behavior is essential yet challenging. In this study, tungsten carbides embedded in carbon spheres (W x C@CS) were fabricated through carburization of organic–inorganic hybrid precursors. W 1.25 C@CS with rational structure-tuning properties exhibits promising regioselectivity (reaching 91.5%) toward aryl C O bond cleavage, specifically during hydrogenolysis of guaiacol to phenol. A structure reconstruction strategy was adopted to elucidate structure–performance relationship by transforming commercially available bulk WC from inert phase to composition-dependent active catalysts. Combined catalytic and characteristic analyses illustrate that the catalyst performance is dependent on the C-defect structure. The intimate connection between the phenol space time yield and the C/W atomic ratio on the exterior interface of the catalyst was verified. The C/W atomic ratio of 7.2 leads to the optimal catalytic performance. Density functional theory calculations were performed to define the catalytic mechanism at the atomic level. The theoretical analysis suggests an appropriate configuration of surface W and C atoms for activation of hydrogen and guaiacol molecules, rendering the intrinsic active sites for phenol production. This work provides insights into controlling the surface compositions of tungsten carbides to develop efficient C O bond cleavage catalysts, which verifies the importance of hydrogenolysis catalysis in lignin-derived compounds involving complex O-containing guaiacols and phenolics.
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JOURNAL OF PHYSICS D-APPLIED PHYSICS
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2018
·Vol. 51
·期 21
·215305
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IF 2.373
Panpan Zhang,Jiupeng Zhao,Ke Zhang,Yiyong Wu,Yao Li
A series of porous polyimide (PI) membranes with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-diaminodiphenyl ether (ODA) in the different ratio of co-solvent (N, N-dimethylacetamide (DMAC)/1, 4-butyrolactone (GBL)) were prepared by a novel wet phase inversion method. The influence of co-solvent on the structure and dielectric properties of membranes were investigated. PI membranes changed from finger-like structure to spongy-like structure with the increasing of the GBL content since the intermolecular interaction between PI induced by GBL. The proportion and size of finger-like structure gradually decreased with the increase of GBL content in DMAC/GBL co-solvent. Although PI membranes exhibited low dielectric permittivity ranges from 1.7–2.5, the dielectric breakdown strengths were also relatively low. In particular, the PI from pure GBL yielded the highest breakdown strength (260.05 kV mm−1) since the low proportion of macrovoids and defects. Moreover, when the ratio of GBL/DAMC was 84/16, the resultant PI membrane possessed a low dielectric constant (1.99) as well as relatively high breakdown strength (100.53 kV mm−1). Therefore, porous PI membraness may be potential in many applications of electronics and microelectronics.
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LIFE SCIENCES
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2018
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IF 3.234
Yijie Zhou,Dan Du,Shuyun Liu,Meng Zhao,Yujia Yuan,Lan Li,Younan Chen,Yanrong Lu,Jingqiu Cheng,Jingping Liu
Aims Ischemic acute kidney injury (AKI) is a serious clinical problem and no efficient therapeutics is available in clinic now. Natural polyacetylene glycosides (PGAs) had shown antioxidant and anti-inflammatory properties, but their effects on kidney injury have not been evaluated. This study aimed to investigate the protective effect of PGA on ischemic kidney injury in renal tubular epithelial cells (TECs) and mice. Main methods Hypoxic HK-2 cells and renal ischemia/reperfusion injury (IRI) mice were treated with PGA from Coreopsis tinctoria , and the cell viability, renal function, apoptosis, inflammation, mitochondrial injury, lipids metabolism were analyzed. Key findings In vitro results showed that PGA improved cell viability and reduced oxidative stress, pro-apoptotic/pro-inflammatory factors expression and NFκB activation in TECs under hypoxia/reperfusion (H/R). Moreover, PGA reduced mitochondria oxidative stress and improved ATP production, ΔΨm and mitochondria biogenesis, and inhibited lipids uptake, biosynthesis and accumulation in hypoxic TECs. In vivo, PGA significantly attenuated kidney injury and reduced blood urea nitrogen (BUN), serum creatinine (CREA) and urinary albumin (Alb), and increased creatinine clearance (CC) in IRI mice. PGA also decreased cell apoptosis, mitochondria oxidative stress, inflammatory response and lipid droplets accumulation, and promoted ATP generation in kidney of IRI mice. Significance Our results proved that PGA ameliorated ischemic kidney injury via synergic anti-inflammation, mitochondria protection and anti-lipotoxicity actions, and it might be a promising multi-target therapy for ischemic AKI.
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MATERIALS CHEMISTRY AND PHYSICS
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2018
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IF 2.21
Zhixiang Jiang,Yue Zhao,Ping Yang
Wire-in-tube and tube-in-tube structures have been prepared using single-spinneret electrospinning method through adjusting the preparation parameters of precursors and subsequent calcined process. Cobalt ferrite (CoFe 2 O 4 ) samples revealed wire-in-tube morphology using a Co/Fe molar ratio of 1/2. In the case of other a Co/Fe molar ratio, belt and porous fiber morphologies were created. Manganese ferrite (MnFe 2 O 4 ) sample exhibited tube-in-tube structure while nickel ferrite (NiFe 2 O 4 ) sample just exhibited tube structure. Because of no template in electrospun polymer composite nanofibers , the precursor diffusion process during calcination plays an important role for morphology controlling. The magnetic properties of samples were examined. The cobalt ferrite (CoFe 2 O 4 ) wire-in-tube sample revealed the highest saturation magnetization (60 emu/g). After growing with AlOOH on the surface, CoFe 2 O 4 wire-in-tube sample revealed a high efficiency for the removal of Congo red pollutant. These nanostructures are particularly attractive for use in the field of nano-fluidic and nano-energy harvesting devices.
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Journal of Materials Chemistry B
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2018
·Vol. 6
·期 42
·6831-6841
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IF 4.776
Lin Huang,Xin-Hua Liu,Xiao-Hong Zhang,Lei Tan,Chuan-Jun Liu
Bacterial infection is posing a great threat to human life, and constructing a platform to capture or kill the bacteria attached on a material surface is of particular significance. Herein, a nano-topographic material surface (SiNW-p-ppix@CDm) has been successfully synthesized based on silicon nanowire (SiNW) arrays modified with a random copolymer, which was decorated with photosensitive protoporphyrin IX (ppix) and β-CD-mannose7 (CDm). The as-prepared surface exhibits a highly efficient bacterial capture, which is based on the co-capture function between the SiNW topographic surface and the bacterial attachment molecule CDm, and sterilization of ppix under irradiation by 630 nm light. The Gram-negative bacterium Escherichia coli (E. coli) was adopted to evaluate the surface bactericidal efficiency. Finally, the killing efficiency can be proved to be 96.7% from fluorescence microscopy after staining with the live/dead bacterial viability kit. The reason for sterilization is that the bacterial cell wall had been split by the reactive oxygen species (ROS), which could be demonstrated via scanning electronic microscopy (SEM). This functional substrate could be used for bacterial enrichment apparatus such as used in water quality monitoring, and even in constructing clinical antibacterial materials.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Zhishan Luo,Min Zhou,Xinchen Wang
In artificial photocatalysis, sluggish kinetics of hole transfer and the high recombination rate of charge have been the Achilles’ heel of photocatalytic conversion efficiency. The development of co-catalysts for promoting exciton splitting and charge separation has therefore gained continuous attention. Herein, “Co 4 O 4 ” cubane complex Co 4 O 4 (O 2 CMe) 4 (py) 4 ( 1a , py = pyridine derivatives), serves as a homogeneous molecular co-catalyst which is engineered into the framework of pristine polymeric carbon nitride (PCN) for water oxidation with light illumination. This modification strategy maximizes the contact areas between co-catalysts and reactants, reduces the over-potential of oxygen producing and accelerates the interface transfer rate of electron-hole pairs, thus leading to enhanced reaction kinetics for photocatalytic water oxidation. Compared with pristine PCN, the photocatalytic O 2 production rate up to 19-fold-enhanced in the presence of molecular co-catalyst. This work emphasizes the importance of developing effective, stable and earth-abundant molecular co-catalysts for the promotion of water-splitting photocatalysis.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
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2019
·Vol. 23
·期 8
·2377-2390
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IF 2.531
Wang Shuangshuang,Feng Jianwei,Meng Qinghan,Cao Bing,Tian Guiying
The search for highly efficient carbon materials with high desalting capacity for the brackish water desalination is still indispensable. In this study, boron and nitrogen co-doped graphene xerogels are prepared by a simple sol-gel method with atmospheric drying and carbonization, in which the rod-like primary particles are attached on the graphene sheets via crosslinking reaction of boric acid-melamine-resorcinol-formaldehyde (BMRF). With the increase in doping ratio, the carbonized BMRF gels display high micropore surface area and abundant doping sites. The maximum doping contents of boron (1.54 at.%) and nitrogen (8.72 at.%) can be achieved in the co-doped graphene xerogel with the molar ratios of C 6 H 6 O 2 and H 3 BO 3 of 1.2, which displays superior specific capacitance (242 F g −1 at a current density of 0.1 A g −1 ) and high capacitance retention (92.7% after 5000 cycles at a current density of 2.0 A g −1 ). The co-doped graphene xerogels are evaluated as electrode materials for the electrochemical desalination of brackish water. Compared to the bare graphene xerogel, the co-doped graphene xerogel displays high electrosorption capacity of 18.45 mg g −1 and high charge efficiency of 45% for NaCl solution under an applied voltage of 1.6 V.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2018
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IF 2.196
Shijie Zhang,Jiaoqiang Zhang,Kaichang Kou,Qian Jia,Yunlong Xu,Ning Liu,Rongzu Hu
2HNIW·HMX co-crystals are crystals composed of HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazisowurtzitane) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), and the HNIW molecule and HMX molecule are combined with noncovalent bonds in a lattice at a 2:1 ratio. The 2HNIW·HMX co-crystals are successfully synthesized by Bolton’s method and characterized by powder X-ray diffraction, laser Raman spectrometer, differential scanning calorimeter (DSC), and high performance liquid chromatograph. The standard enthalpy of formation of 2HNIW·HMX co-crystals is obtained as 861.9 ± 18.6 kJ·mol–1 under the direction of a designed thermochemical cycle with a Calvet microcalorimeter. The thermal decomposition behavior of 2HNIW·HMX co-crystals was studied under the non-isothermal condition with DSC. The apparent activation energy (E) of the decomposition is 332.23 kJ·mol–1 by Kissinger method, 324.10 kJ·mol–1 by Ozawa method, 314.06 ± 4.26 kJ·mol–1 by Friedman–Reich–Levi method, and 306.81 ± 3.12 kJ·mol–1 by NL-INT-SY3 method, respectively. The pre-exponential factor (logA/s–1) is 29.33 ± 0.33 via compensation effect. A continuous Cp mode of Micro-DSC III was used to determine the specific heat capacity (Cp,m) of the target co-crystals from 283.15 to 333.15 K, and the Cp,m is 1114.04 ± 10.92 J·mol–1·K–1 at 298.15 K. These results could provide valuable information on 2HNIW·HMX co-crystals for both theory and application.
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JOURNAL OF LUMINESCENCE
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2018
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IF 2.732
Zengchao Yu,Xiaoxiao Li,Xin Wang,Yanmin Yang
In this paper, Yb 3+ /Er 3+ , Yb 3+ /Tm 3+ and Yb 3+ /Er 3+ /Tm 3+ co-doped β -NaYF 4 up-conversion fluorescent nanoparticles (UCNPs) with an average diameter of 50 nm were successfully synthesized through a thermal decomposition method. The Yb 3+ /Er 3+ co-doped UCNPs possess bright and tunable luminescence varying from green to red as the ratio of Yb 3+ and Er 3+ doping increases. Remarkably, white up-conversion luminescence can be successfully achieved through the incorporation of Tm 3+ . The white light up-conversion efficiency of Yb 3+ /Er 3+ /Tm 3+ co-doped UCNPs dispersed in the solvent have been calculated, suggesting the potentials of the efficient white up-conversion emissions for the multispectral imaging and potential bio-applications.
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Polymers
·
2018
·Vol. 10
·期 9
·934
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IF 2.935
Guangqian Zhu,Xianhui Zhang,Mengmeng Zhao,Liang Wang,Chuyang Jing,Peng Wang,Xiaowu Wang,Qinggang Wang
A series of iminopyridine complexes of Fe(II) and Co(II) complexes bearing fluorinated aryl substituents were synthesized for the polymerization of isoprene. The structures of complexes3a,2band3bwere determined by X-ray diffraction analysis. Complex3acontained two iminopyridine ligands coordinated to the iron metal center forming an octahedral geometry, whereas2badopted a chloro-bridged dimer, and3bfeatured with two patterns of cobalt centers bridged via chlorine atoms. Complexes2band3brepresented rare examples of chlorine bridged bimetallic Co(II) complexes. The fluorine substituents effects, particularly on catalytic activity and polymer properties such as molecular weight and regio-/stereo-selectivity were investigated when these complexes were employed for isoprene polymerization. Among the Fe(II)/methylaluminoxane (MAO) systems, the 4-CF3substituted iminopyridine Fe(II) complex1awas found as a highly active isoprene polymerization catalyst exhibiting the highest activity of 106g·(mol of Fe)−1·h−1. The resultant polymer displayed lower molecular weight (Mn= 3.5 × 104g/mol) and moderate polydispersity index (PDI = 2.1). Furthermore, the ratio ofcis-1,4-/3,4 was not affected by the F substituents. In the series of Co(II)/AlEt2Cl binary systems, complexes containing electron-withdrawing N-aryl substituents (R = 4-CF3, 2,6-2F) afforded higher molecular weights polyisoprene than that was obtained by the complex containing electron-donating N-alkyl substituents (R = octyl). However, ternary components system, complex/MAO/[Ph3C][B(C6F5)4] resulted in low molecular weight polyisoprene (Mn< 2000) with hightrans-1,4-unit (>95%).Keywords:iminopyridine ligands;Fe(II);Co(II) complexes;isoprene polymerization;fluorinated aryl substituents
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