共查询到19条相似文献,搜索用时 194 毫秒
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以具有三维开放网络结构的烧结8 μm-Ni金属纤维(SMF-Ni)为基底, 通过乙烯催化化学气相沉积法在金属纤维表面生长碳纳米管(CNTs), 制备了以金属Ni纤维网络为集流极、CNTs为离子存储库, 尺度跨越宏观、介观和纳米的自支撑薄层大面积CNTs/SMF-Ni(CNTs质量分数为50%)复合电极材料. 用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、N2吸附、脱附等温线和X射线衍射(XRD)等方法对电极材料进行了表征, 并考察了其作为电极对质量分数为0.01%的NaCl水溶液的电容脱盐性能. 自支撑CNTs/SMF-Ni复合电极材料由于具有优异的离子传导和表面电荷传递性能以及较大的介孔表面积, 在1.2 V的工作电压和5 mL/min的水溶液流速下, 对NaCl的电吸附容量和脱盐率分别达159 μmol/g CNTs和57%. 用H2O2对CNTs/SMF-Ni电极材料进行氧化处理后, CNTs表面含氧基团的大量增加增大了材料的亲水性, 从而进一步提升了该复合材料的电容脱盐性能. 相似文献
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芳香醛电合成的研究 Ⅷ 茴香醛合成反应的动力学 总被引:4,自引:0,他引:4
测定了3~40℃范围内不同温度下Ce4+氧化对甲氧基甲苯(MT)制茴香醛(AA)反应的速率常数,并确定了该反应的速率方程为d[AA]/dt=k[MT][Ce4+],表观活化能为31.4±1.3kJ·mol-1. 相似文献
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b-环糊精不仅有增溶作用, 还具有由羟基与反应底物的相互作用所产生的催化作用, 以及由此产生的b-环糊精与反应底物的相互作用对于反应选择性的影响. 在β-环糊精存在下, 以H2O2/H3BO3/H2SO4组成的反应体系, 以水为唯一溶剂, 对甲氧基苯甲醛通过Baeyer-Villiger氧化得到对甲氧基苯酚. β-环糊精可与对甲氧基苯甲醛和对甲氧基苯酚形成包结物, 使反应速率降低, 有效地保护甲氧基, 防止其继续反应, 提高反应的选择性. 采用1H NMR, UV-Vis, FT-IR对β-环糊精与对甲氧基苯甲醛的相互作用进行表征分析, 发现在水相中β-环糊精与对甲氧基苯甲醛可以自发地形成物质的量比为1∶1的包结物, 其吉布斯函变Δγ (298 K)为-14.577 kJ8226;mol-1, 稳定常数Ka为358, 结合FT-IR分析推测出包结物中醛基较多地位于β-环糊精空腔的小口端. 相似文献
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在一室型电解池中, 以饱和CO2的N,N-二甲基甲酰胺(DMF)为溶液, Mg为牺牲阳极, 不锈钢、钛、铜、镍和银为工作电极, 通过电化学方法固定CO2, 在恒电流电解的条件下研究了对甲氧基苯乙酮的电羧化反应, 得到了重要的有机合成中间体2-羟基-2-(4-甲氧基苯基)-丙酸甲酯. 电羧化产率受支持电解质种类、电极材料、电流密度、电解电量和反应温度等影响. 经过反应条件的优化, 目标产物在恒定电流密度为5.0 mA/cm2的条件下产率达到63%. 同时, 以玻碳电极-Pt丝螺旋电极-Ag/AgI/I-为三电极体系, 研究了对甲氧基苯乙酮的电化学行为, 根据底物在通入CO2前后循环伏安图的变化推测了对甲氧基苯乙酮的电羧化反应机理. 相似文献
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以离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)为电解质,采用循环伏安法(CV)、计时电流法(CP)、原位傅里叶变换红外光谱(in situ FTIRS)法等手段研究了对甲氧基甲苯(p-MT)在铂电极上的电氧化行为.实验结果表明:对甲氧基甲苯在离子液体中的电化学氧化反应是受扩散控制的四电子不可逆过程,估算了其扩散系数D=3.4×10-7cm2.s-1,主要电氧化产物为茴香醛,加入适量的水或适当提高温度有利于电氧化反应向生成相应醛的方向进行. 相似文献
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王继双李莉王海燕许鸣镝 《化学分析计量》2023,(6):65-69
建立高效液相色谱法测定化妆品中对羟基苯乙酮、对茴香酸和辛酰羟肟酸含量的分析方法。样品经体积分数为80%的甲醇溶液超声提取,以0.1%(体积分数)磷酸溶液-乙腈作为流动相进行梯度洗脱,采用Osaka Soda Capcell Pak MG C18色谱柱(250 mm×4.6 mm,5μm)进行分离,流量为1.0 mL/min,柱温为30℃,检测波长为210 nm,色谱峰面积外标法定量。对羟基苯乙酮、对茴香酸和辛酰羟肟酸的质量浓度在2.5~60 mg/L范围内与对应色谱峰面积线性关系良好,相关系数均不小于0.999 8,方法检出限均不大于0.22 mg/L。低、中、高三个浓度水平的加标回收率为85.8%~111.1%,测定结果的相对标准偏差为0.5%~5.9%(n=6)。该方法操作简便,适用于化妆品中3种物质的测定。 相似文献
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《International journal of quantum chemistry》2018,118(17)
Iron‐immobilized nanoporous carbon is a well‐known adsorbent used in treating arsenic‐contaminated waters. In this contribution, we present findings on the adsorptive interactions and dynamics of arsenate–goethite cluster ([FeO(OH)]6) with carbon nanotubes (CNTs) using hybridized quantum mechanics/molecular mechanics (QMMM) calculations. The CNTs adsorption mechanism is of interest since a better understanding of the fundamental interactions between arsenate, goethite, and carbon surfaces would translate to advances in CNT‐based adsorbent production and utilization. Novel applications of general amber force field (GAFF) and isobaric‐isothermal Gibbs ensemble Monte Carlo (NpT‐GEMC) methods are described. By the abovementioned methods, we postulate that the [FeO(OH)]6/CNT‐2.3 (diameter 2.3 nm ‐ mesoporous) system enhances the qualitative (i.e., improved chemisorption) rather than the quantitative adsorptive aspect (i.e., total ions adsorbed) in comparison to the [FeO(OH)]6/CNT‐1.6 (diameter 1.6 nm ‐ microporous) system. 相似文献
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Shidong Fei Jinhua Chen Shouzhuo Yao Guohong Deng Lihua Nie Yafei Kuang 《Journal of Solid State Electrochemistry》2005,9(7):498-503
Electroreduction of -glucose to form sorbitol on Zn/CNTs and Zn alloy/CNTs electrodes has been investigated in this paper. Carbon nanotubes (CNTs) used in this paper are grown directly on graphite disks by chemical vapor deposition. Zn and Zn alloy are electrodeposited on the activated CNTs/graphite electrode by pulse galvanostatic method. The micrographs of Zn/CNTs and Zn alloy/CNTs electrodes are characterized by scanning electron microscopy. The results show that the current efficiency of -glucose reduction on CNTs electrodes is much better than that on flat Zn electrodes. The order of the current efficiency on different electrodes is as follows: Zn/CNT (0.58) Zn–Fe/CNT (0.57)>Zn–Ni/CNT (0.43) Zn/graphite (0.42)>Zn (0.40). It indicates that CNTs have good potential application in electrosynthesis. Additionally, effects of some operating parameters, such as pH, temperature and -glucose concentration, on the current efficiency of -glucose reduction are also discussed. 相似文献
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低热固相法制备纳米MnO2/CNT超电容复合电极的循环稳定性 总被引:1,自引:0,他引:1
为了改善纳米MnO2超级电容器电极的充放电循环稳定性,以Mn(OAc)2·4H2O、NH4HCO3和碳纳米管(CNT)为原料,采用低热固相反应得到前驱体,再经焙烧和酸处理,制备了一系列CNT含量不同的纳米MnO2/CNT复合电极材料,并用X射线衍射(XRD)、透射电镜(TEM)和Brunauer-Emmett-Teller(BET)比表面积测定方法对其进行了表征.XRD分析结果表明,复合材料中的MnO2为纳米γ-MnO2.研究了复合电极在1 mol·L-1 LiOH电解质中的电化学性能,并与不含CNT的纯纳米MnO2电极进行了比较.结果表明,含CNTs为10%(w,质最分数,下同)和20%的MnO2/CNT复合电极的循环稳定性远优于纯纳米MnO2电极的循环稳定性,其中含10%CNTs的MnO2/CNT复合电极不仪具有良好的循环稳定性,而且在1000 mA·g-1高倍率充放电条件下仍具有200 F·g-1的高比电容. 相似文献
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Schneider JJ Engstler J Franzka S Hofmann K Albert B Ensling J Gütlich P Hildebrandt P Döpner S Pfleging W Günther B Müller G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(13):2888-2895
The catalytic CVD synthesis, using propyne as carbon precursor and Fe(NO3)3 as catalyst precursor inside porous alumina, gives carbon nanotube (CNT) bags in a well-arranged two-dimensional order. The tubes have the morphology of bags or fibers, since they are completely filled with smaller helicoidal CNTs. This morphology has so far not been reported for CNTs. Owing to the dense filling of the outer mother CNTs with small helicoidal CNTs, the resulting CNT fibers appear to be stiff and show no sign of inflation, as sometimes observed with hollow CNTs. The fiber morphology was observed by raster electron microscopy (REM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The carbon material is graphitic as deduced from spectroscopic studies (X-ray diffraction, Raman and electron energy-loss spectroscopy (EELS)). From M?ssbauer studies, the presence of two different oxidation states (Fe0 and FeIII) of the catalyst is proven. Geometric structuring of the template by two different methods has been studied. Inkjet catalyst printing shows that the tubes can be arranged in defined areas by a simple and easily applied technique. Laser-structuring creates grooves of nanotube fibers embedded in the alumina host. This allows the formation of defined architectures in the microm range. Results on hydrogen absorption and field emission properties of the CNT fibers are reported. 相似文献
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Defeng Wu Tiejun Shi Tao Yang Yurong Sun Linfeng Zhai Weidong Zhou Ming Zhang Jie Zhang 《European Polymer Journal》2011,(3):284-293
Poly(trimethylene terephthalate) (PTT) nanocomposites containing carbon nanotubes (CNTs) with different surface structure and aspect ratio were prepared by melt compounding for electrospinning. The dispersion state of the CNTs in the composites was then examined utilizing rheology tools. The results show that carboxylic surface functionalized CNTs present better dispersion in the matrix than hydroxy surface functionalized CNTs because the former has stronger affinity to the PTT. Besides surface functionalization, the aspect ratio of CNTs is also vital to their final dispersion. The CNTs with lower aspect ratio are dispersed as individuals or small bundles while those with higher aspect ratio are dispersed mainly as flocs with large hydrodynamic radius, showing higher effective volume fraction. The presence of CNTs has a large influence on the morphologies of electrospun fiber and on the appearances of CNTs in the fibers. In the presence of CNTs with lower aspect ratio, continuous composite fibers are obtained. But the structure of those continuous fibers highly depends on the surface group of CNTs. Carboxylic surface functionalized CNTs are well embedded by the PTT and oriented along the fiber axis during electrospinning, leading to bead-free and uniform fiber morphology; while hydroxy surface functionalized CNTs show tortuous conformations with less orientation in the fibers, and as a result, the obtained fibers show beaded and misshaped morphologies. In the case of higher aspect ratio, however, the CNTs prefer to exist as entanglements or knots in the streamlines, and thereby only beaded or even uncontinuous fibers are obtained. Therefore, the formation and fiber morphology of PTT/CNT composite fibers obtained by electrospinning strongly depend on the surface functional groups of the CNTs, as well as on the CNT structure. 相似文献
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Jung JH Hwang GB Lee JE Bae GN 《Langmuir : the ACS journal of surfaces and colloids》2011,27(16):10256-10264
Carbon nanotubes (CNTs) have been widely used in a variety of applications because of their unique structure and excellent mechanical and electrical properties. Additionally, silver (Ag) nanoparticles exhibit broad-spectrum biocidal activity toward many different bacteria, fungi, and viruses. In this study, we prepared Ag-coated CNT hybrid nanoparticles (Ag/CNTs) using aerosol nebulization and thermal evaporation/condensation processes and tested their usefulness for antimicrobial air filtration. Droplets were generated from a CNT suspension using a six-jet collison nebulizer, passed through a diffusion dryer to remove moisture, and entered a thermal tube furnace where silver nanoparticles were generated by thermal evaporation/condensation at ~980 °C in a nitrogen atmosphere. The CNT and Ag nanoparticle aerosols mixed together and attached to each other, forming Ag/CNTs. For physicochemical characterization, the Ag/CNTs were introduced into a scanning mobility particle sizer (SMPS) for size distribution measurements and were sampled by the nanoparticle sampler for morphological and elemental analyses. For antimicrobial air filtration applications, the airborne Ag/CNT particles generated were deposited continuously onto an air filter medium. Physical characteristics (fiber morphology, pressure drop, and filtration efficiency) and biological characteristics (antimicrobial tests against Staphylococcus epidermidis and Escherichia coli bioaerosols) were evaluated. Real-time SMPS and transmission electron microscopy (TEM) data showed that Ag nanoparticles that were <20 nm in diameter were homogeneously dispersed and adhered strongly to the CNT surfaces. Because of the attachment of Ag nanoparticles onto the CNT surfaces, the total particle surface area concentration measured by a nanoparticle surface area monitor (NSAM) was lower than the summation of each Ag nanoparticle and CNT generated. When Ag/CNTs were deposited on the surface of an air filter medium, the antimicrobial activity against test bacterial bioaerosols was enhanced, compared with the deposition of CNTs or Ag nanoparticles alone, whereas the filter pressure drop and bioaerosol filtration efficiency were similar to those of CNT deposition only. At a residence time of 2 h, the relative microbial viabilities of gram-positive S. epidermidis were ~32, 13, 5, and 0.9% on the control, CNT-, Ag nanoparticle-, and Ag/CNT-deposited filters, respectively, and those of gram-negative E. coli were 13, 2.1, 0.4, and 0.1% on the control, CNTs, Ag nanoparticles, and Ag/CNTs, respectively. These Ag/CNT hybrid nanoparticles may be useful for applications in biomedical devices and antibacterial control systems. 相似文献
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Crouse CA Maruyama B Colorado R Back T Barron AR 《Journal of the American Chemical Society》2008,130(25):7946-7954
Carbon nanotubes (CNTs) have been grown using Fe, Co, Ni, and Co/Fe spin-on-catalyst (SOC) systems, involving the metal salt dispersed with a spin-on-glass precursor. During initial growth runs (CH4/H2/900 degrees C), the CNT yield followed the order Co-SOC > Fe-SOC > Ni-SOC. The Fe catalysts produced the longest nanotubes at the expense of a larger average CNT diameter and broader diameter distribution than the Co-SOC system. A series of Co/Fe-SOCs were prepared where as the atomic percentage of Co is increased nucleation of CNT increases but the CNT length decreases. The linear relationship between the diameter and length of CNTs grown from the Co/Fe-SOC suggests that slow growth is beneficial with respect to control over CNT diameter. After initial CNT growth, the original samples were subjected to additional growth runs. Four individual reactions were observed in the Fe-SOC and binary Co/Fe-SOC: regrowth (amplification), double growth (a second CNT growing from a previously active catalyst), CNT etching, and nucleation from initially inactive catalysts (new growth). CNT etching was observed for the mixed catalyst systems (Co/Fe-SOC) but not for either Fe-SOC or Co-SOC. During the regrowth experiments, CNTs were observed that were not present after the initial growth run (and were not as a result of amplification or double growth). Thus, catalysts, which were initially inactive toward nucleation of CNTs in the original growth run, are capable of becoming activated when placed back into the furnace and submitted to regrowth under identical conditions. 相似文献
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在二甲基甲酰胺溶液中,通过简单的沉淀法制备了纳米Ag2CO3和碳纳米管(CNT)的复合物.用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、扫描电镜(SEM)和紫外-可见(UV-Vis)漫反射光谱(DRS)表征了所制备的Ag2CO3/CNT复合物,通过在可见光下降解甲基橙(MO)检测了样品的光催化活性.结果表明,纳米Ag2CO3颗粒与CNT结合良好.CNT的含量为1.5%(w)的Ag2CO3/1.5%CNT复合物活性最高,经过60 min的降解,甲基橙的降解率达到93%.与纯相纳米Ag2CO3比较,CNT的加入还提高了Ag2CO3的稳定性,经过三次循环降解,Ag2CO3/1.5%CNT复合物还能降解81%的甲基橙,而纳米Ag2CO3只能降解59.5%的甲基橙.其活性和稳定性提高的原因是由于CNT的高导电性,它不仅促进了电子-空穴对的分离,还能快速转移产生的光生电子. 相似文献
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本文首先通过溶液混合法将碳纳米管(CNTs)分散到聚碳酸酯(PC)基体中,然后将获得的PC/CNT絮状物通过高温模压的方法制备了一种柔性的高热电性能PC/CNT复合材料。PC/CNT复合材料断面形貌分析表明,CNTs均匀地分散在PC基体中。此外,PC/CNT复合材料的导电性随着CNTs含量的增加而急剧增加,而Seebeck系数几乎保持恒定,使得材料的功率因子随着CNTs含量的增加而快速增加,最大功率因子达到4.6μW·m-1·K-2。 相似文献