Polymers
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2021
·Vol. 13
·期 8
·1329
·
IF 4.329
Maijun Li,Zhibo Zheng,Zhiguang Zhang,Nanwen Li,Siwei Liu,Zhenguo Chi,Jiarui Xu,Yi Zhang
To improve the interfacial compatibility of mixed matrix membranes (MMMs) for gas separation, microporous polyimide particle (AP) was designed, synthesized, and introduced into intrinsic microporous polyimide matrix (6FDA-Durene) to form “all polyimide” MMMs. The AP fillers showed the feature of thermal stability, similar density with polyimide matrix, high porosity, high fractional free volume, large microporous dimension, and interpenetrating network architecture. As expected, the excellent interfacial compatibility between 6FDA-Durene and AP without obvious agglomeration even at a high AP loading of 10 wt.% was observed. As a result, the CO2permeability coefficient of MMM with AP loading as low as 5 wt.% reaches up to 1291.13 Barrer, which is 2.58 times that of the pristine 6FDA-Durene membrane without the significant sacrificing of ideal selectivity of CO2/CH4. The improvement of permeability properties is much better than that of the previously reported MMMs, where high filler content is required to achieve a high permeability increase but usually leads to significant agglomeration or phase separation of fillers. It is believed that the excellent interfacial compatibility between the PI fillers and the PI matrix induce the effective utilization of porosity and free volume of AP fillers during gas transport. Thus, a higher diffusion coefficient of MMMs has been observed than that of the pristine PI membrane. Furthermore, the rigid polyimide fillers also result in the excellent anti-plasticization ability for CO2. The MMMs with a 10 wt.% AP loading shows a CO2plasticization pressure of 300 psi.Keywords:mixed-matrix membranes;compatibility;microporous polyimide particle;polyimide matrix;permeability
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chemosensors
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2020
·Vol. 8
·期 4
·109
·
IF 3.108
Yuhang Zhang,Dongliang Cheng,Zicheng Wu,Feihu Li,Fang Fang,Zili Zhan
The conventional CO electrochemical gas sensor uses aqueous H2SO4solution as electrolyte, with inevitable problems, such as the drying and leakage of electrolyte. Thus, research on new alternative electrolytes is an attractive field in electrochemical gas sensors. In this paper, the application of a new fumed SiO2gel electrolyte was studied in electrochemical gas sensors. The effects of fumed SiO2and H2SO4contents on the performance of the CO gas sensor were investigated. The results showed that the optimized composition of the SiO2gel electrolyte was 4.8% SiO2, 38% H2SO4, and 0.005% polyvinyl alcohol (PVA). Compared with aqueous H2SO4, the gel electrolyte had better water retention ability. The signal current of the sensor was proportional to the CO concentration. The sensitivity to CO was 78.6 nA/ppm, and the response and recovery times were 31 and 38 s, respectively. The detection limit was 2 ppm. The linear range was from 2 to 500 ppm. The gel electrolyte CO sensor possesses equivalent performance to that with aqueous electrolyte.Keywords:fumed SiO2;gel electrolyte;electrochemical sensor;CO gas sensor
研究领域:
材料科学
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传感器技术
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环境监测
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
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2020
·
IF 6.155
Xiao You,Jinshan Yang,Mengmeng Wang,Hongda Wang,Le Gao,Shaoming Dong
In this work, the interconnected graphene scaffolds are prepared by three-dimensional (3D) printing for multifunctional gas detection with tunable sensitivity. The scaffolds with regularly aligned graphene conductive networks exhibit significant mechanical strength and high electrical stability to multi-direction deformation, which can be attributed to the typical core-shell structure of graphene and PVP. The resistance of the free-standing scaffolds can realize the real-time response to H 2 O and NO 2 , and the relative resistance change to 100 ppm H 2 O and 100 ppm NO 2 can reach 2% and 2.5 %, respectively. The charge doping of the oxidizing gases is considered to be the main reason for various response sensitivities of the scaffolds with different orthogonal layers, in which the interconnected conductive network can generate a large specific surface area and significantly improving the adsorption of the target gases and the transfer of charge. The controllable fabrication of regular structure has appropriately great potential for further optimizations and applications in gas detection.
研究领域:
材料科学
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传感器技术
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
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2011
·
IF 2.356
Xueting Chang,Shibin Sun,Yansheng Yin
In this paper, orthorhombic tungsten trioxide monohydrate nanosheets in high yields were successfully generated using a very simple sonochemical method with tungsten hexachloride as the precursor and distilled water as the solvent. The tungsten trioxide monohydrate nanosheets exhibited thickness of about tens of nanometers and edge length of up to several hundreds of nanometers. The sheet-like morphology has been well explained based on the acoustic cavitation effect as well as the crystalline structure of orthorhombic tungsten trioxide monohydrate. The tungsten trioxide monohydrate nanosheets sensor exhibited ideal room-temperature gas-sensing performances, and were found to be sensitive to various flammable organic vapors and harmful gases. The corresponding sensing mechanisms were also discussed.
研究领域:
材料科学
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传感技术
✓ 已验证
产品关联
DOI
高影响因子
THIN SOLID FILMS
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2016
·
IF 1.761
Min Li,Wenkai Zhang,Gang Shao,Hao Kan,Zhilong Song,Songman Xu,Haoxiong Yu,Shenglin Jiang,Jingting Luo,Huan Liu
Colloidal quantum dots (CQDs) are emerging as ideal building blocks for the development of sensitive and low-cost gas sensors because of their large surface area and solution processability. So far, the construction of CQD gas sensor is limited to lab-scale, batch-processing methods such as spin coating . Here, we demonstrated highly sensitive and fast-response CQD gas sensors through a room-temperature spray-coating route in ambient air. Unlike the spin-coating process, a porous film morphology could be achieved by the spray-coating of ultrasmall PbS CQDs (4.0 nm in diameter) on the alumina ceramic substrates , possibly explaining their superior gas-sensing performance. Moreover, we investigated the effect of the dispersing solvent on the spray-coated PbS CQD films and found that organic solvents with lower boiling point were preferred in producing porous and sensitive CQD films. The response of the optimal gas sensors toward 50 ppm of NO 2 at room temperature was high as 44, with response and recovery times short as 1 s and 28 s, respectively. The enhanced gas-sensing capabilities, coupled with the promise for mass production at room temperature, make the spray-coated CQD gas sensors very attractive in the future gas-sensing technology.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2016
·
IF 1.045
Guangliang Song,Lina Wang,Dandan Liu,Jianan Yao,Yiming Cao
A series of polyimide (PI) membranes were prepared based on three triphenylamine-based diamines, namely 4,4′-diaminotriphenylamine, 4,4′-diamino-3′′,5′′-dimethyltriphenylamine, and 4,4′-diamino-3′′,5′′-ditrifluoromethyltriphenylamine, via thermal imidization procedure. The PI membranes displayed good thermal properties, with glass transition temperatures of 279–341°C and 5% weight loss temperatures above 515°C under a nitrogen atmosphere. The gas permeation properties of the membranes were investigated and interpreted from the viewpoint of the PI backbone structure. The gas permeation coefficients increased as the substituent pendant groups at the 3′′,5′′ positions of the triphenylamine varied from –H to –CH3 and –CF3, and the permselectivity of gas pairs (including hydrogen/nitrogen (N2), oxygen/N2, carbon dioxide (CO2)/N2, and CO2/methane) decreased in this order. The diffusion coefficients and solubility coefficients were calculated, and the results revealed the variation of the substituted triphenylamine units principally influenced the diffusion coefficients, indicating that the substituted triphenylamine affected the gas transport properties by “diffusivity-controlled” modification.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
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2018
·
IF 6.042
Jingni Fu,Luning Zhang
A fluorescence spectroscopic assay using Newton black film (NBF) for sensitive and selective detection of gaseous formaldehyde at room temperature is reported. The method relies on the Hantzsch reaction of formaldehyde with ammonium citrate and acetylacetone, plus a combination of the large surface area-to-volume ratio (5 × 108 m–1) and efficient uptake of gas by the nanometer-thick aqueous core of NBF. The assay has a limit of detection (LOD) of 4 ppb, a linear signal-to-concentration correlation up to 300 ppb of HCHO gas in the air, and a nonlinear monotonic increasing correlation in the range of 300 ppb to 1.2 ppm. It is unaffected by relevant analytes such as acetaldehyde, benzaldehyde, acetone, and propionaldehyde. We also demonstrate the sensing of formaldehyde outgassing from a plywood sample using this method and the results agree with the factory specifications.
研究领域:
分析化学
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Bowen Tian,Bin Zhao,Fei Feng,Fan Luo,Haimei Zhou,Xiaohong Ge,Wu Yanhong,Xinxin Li
In this paper, a novel embeded elliptic cylindrical posts (ECPs) with large surface area and wide effective width, which could support more stationary phase and decrease the pressure drop, is applied on the micro-fabricated gas chromatographic (μGC) column. Compared with μGC column with cylindrical posts (CPs), the surface area and effective width of μGC column with ECPs are increased by 29% and 30%. Separation experiments are performed under the same head pressure at column inlet: in experiments of separating mixture 1, the column efficiency of the μGC column with ECPs for C9 has a 76% improvement, and the separation resolution between C8 and C9 also has a 34% improvement; in experiments of separating mixture 2, seven kinds of analytes can be identified by the μGC column with ECPs less than ten minutes, while, only six kinds can be identified by the μGC column with CPs in almost the same time. In detail, the column efficiency of the μGC column with ECPs for toluene has a 129% improvement, and the separation resolution between benzene and toluene also has a 56.4% improvement. Hence, the μGC column with the inner structures of ECPs is a valid means to improve column efficiency and resolution in a lower pressure drop.
研究领域:
分析化学
·
微流控技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 22
·14055-14063
·
IF 3.442
Wang Yu-Chong,Sun Zhong-Sen,Wang Su-Zhen,Wang Shu-Ying,Cai Sheng-Xun,Huang Xin-Yu,Li Ke,Chi Zong-Tao,Pan Shu-Di,Xie Wan-Feng
Metal oxide semiconductor sensors based on nanocrystalline In 2 O 3 and its composites are found to be very sensitive in detecting low-concentration (~ 5 ppm) gases such as ozone, nitrogen dioxide, formaldehyde and butane. Here, we successfully obtained fiber-shaped In 2 O 3 crystalline nanofibers via electrospun and calcination routes. The gas sensing properties of the In 2 O 3 nanofibers were studied by exposing them to the acetic acid vapor with different concentrations from 500 ppb to 2000 ppm at the optimum operating temperature (250 °C). The device possesses ultra-high response of 66.7 toward 2000 ppm acetic acid vapor, low response and recovery times of 25 s and 37 s (100 ppm), respectively, and significant selectivity to acetic acid at 100 ppm. In particular, the sensor based on In 2 O 3 nanofibers has very low detection limit and can reach 500 ppb. Therefore, the presented In 2 O 3 nanofiber sensor can be used in practice in acetic acid detection area in the future.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Royal Society Open Science
·
2019
·Vol. 6
·期 3
·
IF 2.515
Zhanyang Gao,Min Wang,Shiyao Wang,Yi Wang,Ruichao Peng,Ping Yu,Yunbai Luo
A novel and efficient preparation route of insulating gas-heptafluoroisobutyronitrile was developed. The synthetic route involved halogen-exchange fluorination, decomposition of bis-(perfluoroisopropyl) ketone and dehydration reaction. Overall, the desired compound was produced without the use of extremely toxic and expensive substances. Structures of the as-obtained products were determined by 19F NMR, 13C NMR, IR and GC-MS. The effects of several variables on reaction yield including nature of potassium fluoride, the catalyst dosage, temperature, solvent and molar ratio of raw materials were all investigated. The results indicated that the total yield of heptafluoroisobutyronitrile could reach 42% from original materials under optimal conditions and the mechanism of the reaction was proposed.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 11
·4558-4569
·
IF 3.553
Li Tianya,Wang Kejian,Wang Jihao,Liu Yueqi,Han Yufen,Song Jinghui,Hu Hengwei,Lin Guangyi,Liu Yong
Proton exchange membrane fuel cell (PEMFC) is a promising automotive power source that has been gradually applied due to its many advantages such as pollution-free and low-temperature start-up. The gas diffusion layer (GDL) is a key component for water and gas management in PEMFC. It can directly affect the performance of PEMFC. In this paper, we prepared a new type of GDL with hierarchical pores to improve the performance of PEMFC at high current density. The new GDL mainly includes a commercial carbon paper layer and two microporous layers on the same side of carbon paper. The microporous layer near carbon paper was modified with pore former, and another layer was produced without pore former. The pore size of the middle microporous layer was controlled by the content of pore former and times of sonication. From the results of the polarization curve, electrochemical impedance spectroscopy, water contact angle, conductivity, and pore size distribution, it was found that GDL with hierarchical pores shows obvious advancement than commercial GDL. The PEMFC performance was tested to compare the new and commercial GDL. The results show that the peak power of our GDL at 100% humidity reaches 1.24 W/cm 2 and the limit current density is 3.500 A/cm 2 . The modification of the pore size of the microporous layer near the carbon paper side can improve the water management ability of the fuel cell.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Shan Xu,Xiaolong Ren,Ning Zhao,Lei Wu,Zhiguang Zhang,Yanfang Fan,Nanwen Li
The CO 2 -induced plasticization effects impose detrimental effects on polymeric membranes separation performance. To address this issue, a high-performance crosslinked brominated 6FDA-based polyimide (BMPI) is developed in this work, exhibiting highly suppressed plasticizing effects. The permeability and selectivity of polyimide precursor membranes are tuned by introducing bromine atoms into the polyimide structure, creating a best performing membrane with bromination degree of 60%. The membrane CO 2 permeability reaches 395 Barrer, and the selectivity of CO 2 /CH 4 increases from 22.0 for a non-brominated analogue to 26.0. The debromination induced crosslinked BMPI membranes are achieved upon thermal treatment within the temperature range of 150 °C–350 °C with varied crosslinking degree, resulting in large differences for the membrane separation performance. The completely crosslinked BMPI treated at 350 °C for 10 h demonstrates high CO 2 permeability of 483.6 Barrer and the CO 2 /CH 4 selectivity of 26.0. Most importantly, the crosslinking reaction greatly stabilizes the membrane performance against plasticization under high CO 2 feed pressure. Compared with the non-crosslinked membranes with a plasticizing pressure of 150 psia, the plasticization for the crosslinked membrane occurs at high CO 2 pressure of 600 psia. This study provides a facile approach for the preparation of high-performance gas separation polymeric membranes with enhanced plasticization resistance.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
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