MICROPOROUS AND MESOPOROUS MATERIALS
·
2015
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IF 3.453
Hong Jiang,Qing Yan,Rizhi Chen,Weihong Xing
Pd@ZIF-8 nanoparticles with uniform size and morphology were prepared via an assembly method that enables the crystallization of ZIF-8 in methanol in the presence of polyvinylpyrrolidone (PVP)-modified Pd nanoparticles. The molar ratios of Pd/Zn 2+ and 2-methylimidazole (Hmim)/Zn 2+ are important parameters affecting the physical and catalytic properties of the Pd@ZIF-8. The catalytic activities of the hybrid catalysts were evaluated by the hydrogenation of p -nitrophenol to p -aminophenol. The results indicate that the increase of Pd loading and p -nitrophenol conversion can be tuned by adding more amounts of PVP-Pd colloid, but a suitable amount of PVP-Pd (Pd/Zn 2+ ≤ 0.012) is helpful to the control of particle size of Pd@ZIF-8 and encapsulation of the Pd nanoparticles within the ZIF-8 crystals. Pd@ZIF-8 catalysts prepared with excessive or equal molar of Hmim relative to Zn 2+ have similar morphology and uniform particle size, where the Pd nanoparticles are fully confined within the ZIF-8 crystals without aggregation. Furthermore, the Pd@ZIF-8 catalysts exhibit the better catalytic performance for the p -nitrophenol hydrogenation owing to the high loading of well-dispersed Pd nanoparticles with the decreased Hmim/Zn 2+ molar ratio. This work would aid the development of high-performance Pd@ZIF-8 catalysts.
研究领域:
材料科学
·
催化化学
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DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2018
·Vol. 48
·期 1
·286-295
·
IF 1.566
Zhang Chi,Xia Yong,Lian Linyuan,Fu Xiaoming,Yin Liping,Zhang Jianbing,Luo Wei,Miao Xiangshui,Zhang Daoli
Copper indium sulfide (CIS) quantum dots (QDs) are attractive as potential optoelectronic devices, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, CIS QDs should be hydrophilic in certain applications. In this present work, hydrophilic CIS and CIS/ZnS colloidal QDs were synthesized by a one-pot environmentally-friendly route employing N , N -dimethylformamide (DMF) as the solvent and in situ generated H 2 S as the sulphur precursor. The effect of stoichiometry was investigated by varying the feeding molar ratios of Cu/In, which did not affect the crystalline structure of the CIS colloidal QDs, while the optical property was influenced significantly. With the decrease of the feeding molar ratios of Cu/In, the band gap of the resulting CIS colloidal QDs had blue-shifts and relative photoluminescence quantum yield of the corresponding CIS/ZnS colloidal QDs increased monotonically.
研究领域:
材料科学
·
光学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Shunqin Luo,Chao Tang,Zhaohui Huang,Chen Liu,Jiawei Chen,Minghao Fang
In this study, bismuth oxyiodide/titanium dioxide (BiOI/TiO 2 ) heterostructures with different molar ratios of Bi and Ti were synthesized by electrospinning and hydrothermal methods . The samples thus synthesized were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy . The results confirmed the presence of the BiOI/TiO 2 heterojunction with Bi/Ti molar ratios of 0.20–1 by electrospinning and hydrothermal methods . Photocatalytic activity was also evaluated by the degradation of methylene blue (MB) under visible-light irradiation. The 80% BiOI/TiO 2 heterostructure exhibited the best photocatalytic activity for the degradation of MB under visible-light irradiation.
研究领域:
材料科学
·
环境科学
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DOI
高影响因子
Desalination and Water Treatment
·
2016
·
IF 1.272
Na Han,Sumei Chen,Guo Chen,Xuefeng Gao,Xingxiang Zhang
We report the preparation and performance of poly(acrylonitrile-methacrylate) (AN-MA) flat-sheet membranes with various MA feeding ratio via thermally induced phase separation, in which the membrane forming system consisted of AN-MA, ethylene carbonate (EC), and triethyl citrate (TEC). The effects of the preparation conditions, such as the MA feeding mole ratio, EC content in the mixed diluent, and AN-MA concentration on the pore structure, porosity, water flux, and mechanical properties of the AN-MA membranes were studied. The poly(acrylonitrile-methacrylate) (AN-MA mole ratio 85/15, 80/20, 75/25) copolymers were synthesized by emulsion polymerization. The AN-MA copolymers are melt processable in the temperature range of 130–180°C. The morphology of the resulting membrane gradually changes from a typical bicontinuous structure to a cellular structure upon increasing the polymer concentration and EC content in the mixed diluent. The water flux of AN-MA microporous membranes increased and subsequently declined as the MA feeding molar ratio increased in the polymerization system. In addition, the mechanical properties of the AN-MA membranes increased gradually. Consequently, the properties of the AN-MA membranes were optimal when the MA feeding molar ratio was 20 mol%. Correspondingly, the membrane exhibits a relatively high water flux (66.0 L/(m2 h)) and porosity (75%) when the ternary system contains 60 wt.% EC in the mixed diluent and 9 wt.% 80/20AN-MA. In addition, the membrane exhibits a higher tensile strength (4.6 MPa) and elongation (43.8%).
研究领域:
材料科学
·
化学工程
·
膜技术
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DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2018
·
IF 3.849
Xue-Dan Hou,Kai-Peng Lin,Ao-Lin Li,Lu-Min Yang,Ming-Hui Fu
Effective obtaining fermentable sugar s and other platform chemicals from rice straw mediated by choline chloride- oxalic acid dihydrate (CO) and the corresponding micro-mechanism investigation were conducted in this work. Choosing a suitable constituents molar ratio of CO appeared to be a feasible method to achieve an appropriate pretreatment severity for a good biomass fractionation. Pretreatment by using CO with high oxalic acid dihydrate to choline chloride molar ratio could afford easily digestible cellulose-rich materials (CMRs, >80% of enzymatic digestion) and lignin-rich materials (LRMs) of high purity (>82%) due to extensive hemicellulose removal (>93%) and delignification (around 70%). Cell wall microstructure characterizations based on confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM) verified the stronger xylan and lignin removal ability of CO with higher oxalic acid dihydrate content. Moreover, the considerable removal of xylan confirmed by CLSM was beneficial to delignification and the subsequent cellulose enzymatic hydrolysis. Furthermore, ultra-structural changes of lignin distribution in cell walls based on TEM indicated the occurrence of partial delignification, preferentially in cell corner (CC) and compound middle lumen (CML) rather than in the secondary cell walls. These findings provides a new insight into the detailed mechanism of acidic DESs mediated biomass deconstruction.
研究领域:
生物化学
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生物质能
·
环境科学
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产品关联
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2016
·
IF 2.101
Dong Feng,Xudong Luo,Guodong Zhang,Zhipeng Xie
In order to determine the relationship between the property of MgOAl 2 O 3 SiO 2 composite ceramics and molar ratios of MgO/Al 2 O 3 , especially the sintering behavior and thermal shock resistance, the MgOAl 2 O 3 SiO 2 composite ceramics were fabricated with micro-size MgO , Al 2 O 3 powder and nano-size SiO 2 as main raw materials. The sample was characterized by phase analysis, densification and thermal shock times. Moreover, field emission scanning electron microscope was also conducted to study microstructure of the samples before and after thermal shock. Effect of different molar ratios of MgO/Al 2 O 3 on the sintering behavior and thermal shock resistance of composite ceramics were investigated. The results showed that the sample possess better sintering behavior and thermal shock resistance with the molar ratio of MgO/Al 2 O 3 equal to 2/1. Grains of periclase and spinel were directly bonded together, resulting in a dense and compact microstructure, and the bulk density of obtained sample reached 3.4 g/cm 3 . The microstructure of sample after thermal shock revealed that the crack propagation path was deflected and bifurcated, the main-crack propagation was restricted and more fracture energy was consumed, the thermal shock resistance of composite ceramics was greatly improved.
研究领域:
材料科学
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陶瓷工程
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产品关联
DOI
高影响因子
International Journal of Minerals Metallurgy and Materials
·
2021
·Vol. 28
·期 11
·1868-1874
·
IF 2.232
Xiong Shan-xia,Kuang Jian-lei,Zheng Qian-fang,Xiao Ting,Liu Wen-xiu,Wang Qi,Jiang Peng,Cao Wen-bin
Wood-based panels containing urea-formaldehyde resin result in the long-term release of formaldehyde and threaten human health. In this study, inorganic aluminosilicate coatings prepared by combining metakaolin, silica fume, NaOH, and H 2 O were applied to the surfaces of wood-based panels to obstruct formaldehyde release. The Si/Al, Na/Al, and H 2 O/Na 2 O molar ratios of the coatings were regulated to investigate their effects on the structure and formaldehyde-resistant barrier properties of coatings. Results showed that the cracks in the coatings gradually disappeared and the formaldehyde resistance rates of the barrier increased as the Si/Al molar ratio was increased from 1.6 to 2.2. This value also increased as the Na/Al molar ratio was increased from 0.9 to 1.2 because of the improvement of the degree of polymerization. As the H 2 O/Na 2 O molar ratio was increased from 12 to 15, the thickness of the dry film decreased gradually and led to the reduction in the formaldehyde resistance rate. When the Si/Al, Na/Al, and H 2 O/Na 2 O molar ratios were 2.2, 1.2, and 12, respectively, the inorganic aluminosilicate coating showed good performance as a formaldehyde-resistant barrier and its formaldehyde resistance rate could reach up to 83.2%.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Yujie Zhang,Changjian Wang,Jun Liang,Mengmeng Wang,Yingjuan Fu,Yongchao Zhang,Guoyu Tian,Zhaojiang Wang
This study explored the synthesis of lignin-polyol (LP) by liquefaction of Kraft lignin in polyethylene glycol and glycerol. LP23 (23 wt% lignin) and LP41 (41 wt% lignin) were obtained with remarkable liquefaction yields of 97.43 % and 93.75 %, respectively. LP-based polyurethane film (LP-PUF) was then fabricated by reacting LP23 and LP41 with hexamethylene diisocyanate. Mechanical properties and hydrophobicity of LP-PUF were optimized by varying NCO/OH molar ratios. LP23-PUF1.9 with NCO/OH of 1.9 showed excellent tensile strength of 34.28 MPa and Young's modulus of 233.27 MPa, while LP41-PUF2.0 with NCO/OH of 2.0 exhibited good tensile strength of 26.03 MPa and Young's modulus of 260.66 MPa. LP23-PUF2.0 displayed high hydrophobicity as indicated by the water contact angle of 96.8° and low surface free energy of 15.68 mN/m. Glass transition temperature (Tg) of LP-PUF varied depending on lignin content and NCO/OH molar ratio. Specifically, the increase of KL content from 23 % to 42 % induced big rise of Tg by 8 °C. The NCO/OH induced change of Tg was relatively weak, as indicated by the small increase of −2.71 °C of LP41-PU1.4 to −1.81 °C of LP41-PUF2.0. The results of this work offer insights for lignin utilization as structural component of high modulus and high strength polyurethane film.
研究领域:
材料科学
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化学工程
·
高分子科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF BIOSCIENCE AND BIOENGINEERING
·
2018
·
IF 2.015
Ao-Lin Li,Xue-Dan Hou,Kai-Peng Lin,Xuan Zhang,Ming-Hui Fu
Lignocellulosic biomass pretreatment with deep eutectic solvents (DESs) is a promising and challenging process for production of biofuels and valuable platform chemicals. In this work, rice straw was mainly fractionated into carbohydrate-rich materials (CRMs) and lignin-rich materials (LRMs) by 90% lactic acid/choline chloride (LC)-water solution with different molar ratio of hydrogen bond donor (HBD, lactic acid) and hydrogen bond acceptor (HBA, choline chloride). It was found that high HBD/HBA molar ratio of DESs was favorable for achieving CRMs and LRMs with high purity, and both HBD and HBA were responsible for effective biomass fractionation possibly due to their synergistic effect on highly efficient breakage of the linkage between hemicellulose and lignin and thus lignin extraction. About 30%–35% of lignin in native rice straw was fractionated as LRMs, and exceeding 70% of xylan were removed and fractionated into the liquid stream as forms of xylose , furfural and humins after pretreatment using aqueous LC (3:1, 5:1) solution. Consequently, polysaccharides enzymatic hydrolysis of the CRMs were significantly enhanced. Moreover, all the DESs could be recovered with high yields of around 90%, and 69% of the LC (3:1) was recovered after 5 cycles reuse at 90 °C. Besides, the recycled DES maintained a good pretreatment ability, and glucose yields of 60–70% were achieved in the enzymatic hydrolysis of CRMs obtained in each cycle. The facile process established in present work is promising for large scale production of fermentable sugars and other chemicals.
研究领域:
生物化学
·
可再生能源
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产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 45
·15947-15953
·
IF 4.029
Ming Zhong,Dong-Hui Yang,Ling-Jun Kong,Wei Shuang,Ying-Hui Zhang,Xian-He Bu
Developing high-performance electrode materials to replace a traditional graphite electrode is critical for the commercialization of lithium ion batteries, which however still remains a great challenge. Herein, we report a suitable method to synthesize a series of well-dispersed nanostructured Co3O4–CoFe2O4 composites (CCFs) from bimetallic metal–organic frameworks (BiMOFs) with varied Fe3+/Co2+ molar ratios. When used as anodes for lithium ion batteries, the CCF-12 composite exhibits a maximum initial discharge capacity of 1328 mA h g−1, a reversible capacity of 940 mA h g−1 at 100 mA g−1 after 80 cycles, and a better rate capability in comparison with those of pure Co3O4 and other CCF composites. The well-dispersed structure and small particle size are believed to mainly contribute to the outstanding electrochemical performance of CCF-12 electrodes.
研究领域:
材料科学
·
电化学
·
纳米科技
·
能源存储
·
无机化学
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DOI
高影响因子
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
·
2024
·Vol. 129
·期 4
·e2023JE008031
·
IF 3.9
Xinyi Xiang,Peixin Du,Binlong Ye,Hongling Bu,Dong Liu,Jiacheng Liu,Jian Hua,Xiaolong Guo
Ferrihydrite, a nanocrystalline iron (oxyhydr)oxide mineral, is widely distributed in soils and sediments on Earth and is probably an important component and/or precursor of widespread nanophase iron minerals on Mars. Terrestrial ferrihydrite often co-occurs with amorphous silica and/or contains a certain amount of Si in its structure. However, it remains ambiguous how environmental Si concentration affects the formation-evolution and structure-spectral features of ferrihydrite in the Fe(III)-Si systems. To this end, hydrolysis experiments were carried out for Fe-Si systems at an unprecedentedly wide range of initial Si/(Fe + Si) molar ratios (0–0.80), followed by characterizing the products detailly. X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, Mössbauer spectroscopy, and transmission electron microscopy results showed that at Si/(Fe + Si) molar ratios ≤0.30, the main phase of the products was ferrihydrite, of which the unit cells enlarged, the crystallinity decreased, and the existing state of Fe changed with increased Si contents; at Si/(Fe + Si) molar ratios ≥0.40, ferrihydrite was no longer formed and a novel amorphous Fe-O-Si phase was instead obtained, with the excess Si forming amorphous silica. The visible and near-infrared spectroscopy, the most powerful tool to detect hydrous minerals on the surface of Mars at global or regional scales, showed weakness in identifying ferrihydrite-like materials obtained in the Fe-Si systems. Raman spectroscopy can identify ferrihydrite and Si-containing ferrihydrite but cannot differentiate between them. Mössbauer spectroscopy showed great potential in both identifying and differentiating between ferrihydrite and Si-containing ferrihydrite, and thus can be used to characterize the poorly ordered iron (oxyhydr)oxides on Mars. Key Points Hydrolysis experiments of Fe(III)-Si systems were performed at an unprecedentedly wide range of initial Si/(Fe + Si) molar ratios (0∼0.80) The environmental Si concentration controls the formation and evolution of ferrihydrite in the Fe(III)-Si systems Mössbauer spectroscopy shows great potential in identifying and differentiating between ferrihydrite-like materials Plain Language Summary On the surface of ancient Mars where liquid water was available, Fe-Si hydrolysis systems were likely common as a result of the high abundances of Fe and Si in the crust of Mars. By performing hydrolysis experiments of Fe-Si systems at an unprecedented wide range of Si/(Fe + Si) molar ratios, we found that the hydrolysis products of Fe-Si systems varied among combinations of ferrihydrite, Si-containing ferrihydrite, an unknown Fe-O-Si phase, and amorphous silica. We also found that the visible and near-infrared reflectance spectroscopy, the most powerful tool to remotely detect hydrous minerals on the surface of Mars at global and regional scales, showed weakness in identifying ferrihydrite, Si-containing ferrihydrite, and the novel Fe-O-Si phase; Raman can be used to identify ferrihydrite-like materials but cannot be used to differentiate between ferrihydrite and Si-containing ferrihydrite; mid-infrared spectroscopy can differentiate ferrihydrite from Si-containing ferrihydrite and the novel Fe-O-Si phase; Mössbauer spectroscopy (recorded at varied temperatures) provided clues to identifying and further differentiating between ferrihydrite-like materials and thus holds great potential for detecting Fe/Si-rich phases on the surface of Mars.
研究领域:
地质学
·
行星科学
·
矿物学
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DOI
高影响因子
COMBUSTION AND FLAME
·
2026
·
IF 5.9
Tengyue Song,Yuhuai Shi,Shuhan Guo,Ying Kang,Peijia Li,Yuhao Wu,Xiong Cao
The development of highly efficient catalysts for regulating thermal decomposition and combustion behavior of energetic components is of great significance. This study successfully designed, synthesized and characterized a series of nickel-iron layered double oxide doped graphitic carbon nitride (NFL@CN-X, X = 1, 3, 5) composite combustion catalysts with varying Ni/Fe molar ratios through electrostatic self-assembly followed by thermal treatment. These catalysts exhibit well-developed porous structures and highly active metal centers. The effects of these catalysts on the thermal decomposition behavior of Ammonium perchlorate (AP), Cyclotrimethylene trinitramine (RDX), Cyclotetramethylene tetranitramine (HMX) and Hexanitrohexaazaisowurtzitane (CL-20) were systematically investigated using differential scanning calorimetry (DSC) and thermogravimetric (TG) analyses, and relevant kinetic and thermodynamic parameters were calculated. In addition, the optimal catalyst was employed for ignition experiments, and high-speed camera technology was employed to evaluate their impact on the combustion performance of various energetic composite systems. Furthermore, a potential catalytic mechanism was proposed using HMX as a representative energetic compound, based on thermogravimetric-mass spectrometry (TG-MS) analysis. The DSC and TG results revealed that the incorporation of NFL@CN-X ( X = 1, 3, 5) significantly lowered the peak decomposition temperatures (T p ) of AP, RDX, HMX and CL-20 by 73.6∼81.0 °C, 1.3∼2.4 °C, 1.1∼1.5 °C, and 5.1∼7.7 °C, respectively. Correspondingly, the apparent activation energies (E a ) of the energetic composite systems markedly reduced by 113.41∼140.86 kJ·mol −1 , 3.44∼29.85 kJ·mol −1 , 32.73∼134.58 kJ·mol −1 , and 49.77∼66.74 kJ·mol −1 compared with those of the raw samples, respectively. Among these, NFL@CN-5 exhibited the most pronounced catalytic thermal decomposition effect and also significantly enhanced combustion characteristics and energy release efficiency of energetic composite systems. Ignition experiments further demonstrate that energetic systems incorporating NFL@CN-5 exhibit increased flame heights, prolonged combustion durations, and more complete combustion behavior. The NFL@CN series catalysts show great potential as superior alternatives to conventional combustion catalysts.
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）