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Fenqi Du Dongmei Yang Yue Sun Yang Jiao Feng Teng Haibo Fan 《Ceramics International》2021,47(4):4963-4971
Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga2O3 nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga2O3 nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga2O3/ZnGa2O4 hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga2O3 nanomaterials. 相似文献
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以三嵌段共聚物F127和P123为模板剂,线性酚醛树脂(PF)为炭前驱体,利用有机-有机自组装制备了具有二维六方结构和蠕虫结构的介孔炭.采用XRD、TEM、N2吸附/脱附等方法对介孔炭的结构进行了表征,研究了模板剂用量和模板剂类型对上述介孔炭结构的影响.结果表明:当模板剂F127与PF的质量比由1:2变为1:1时,所得介孔炭的孔壁厚度有所下降,但比表面积、孔容和孔径分别从576 m2·g-1、0.29 cm3·g-1和2.7 nm提高到670m2·g-1、0.40 cm3· g-1和3.2 nm;分别以F127和P123为模板剂制备的介孔炭F-1-500和P-1-500的孔径大小基本相同,但P-1-500的孔壁厚度相对于F-1-500降低了37.4%,且有序性下降,仅能得到蠕虫状结构. 相似文献
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Pore structure control of mesoporous carbon monoliths derived from mixtures of phenolic resin and ethylene glycol 总被引:1,自引:0,他引:1
Mesoporous carbon monoliths derived from phenolic resin mixtures have been prepared in the process based on polymerization-induced phase separation. The effect of the composition of resin mixtures and the resin curing temperature on the pore structure of carbon monoliths has been systematically investigated, with emphasis on controlling the apparent porosity and pore size distribution. Fractal dimensions have been introduced to evaluate the morphologies of the carbon monoliths. The results showed that mesoporous carbon monoliths with narrow pore size distribution were obtained. The pore structure of carbon monoliths could be controlled by changing the resin curing temperature and the content of ethylene glycol, curing catalyst and water in the resin mixtures. The apparent porosity of carbon monoliths varied from 54.27% to 26.83%. Carbon monoliths had narrower pore size distribution when more ethylene glycol and higher resin curing temperature were employed. The pore structure of carbon monoliths would be changed radically when the initial resin samples were prepared with excess water (9.8 wt%), i.e. porous carbon foams with sponge structure were obtained. Carbon monoliths inherit their porosity from precursing cured resins where it was formed as a result of phase separation of resin-rich and glycol-rich phases. Volume contraction had certain effect on the pore structure of carbon monoliths. 相似文献
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The oxidation of carbon derived from phenolic resin and heat-treated at temperatures ranging from 1000 to 2400°C for 1 hr was studied in a flowing oxygen atmosphere at temperatures between 424 and 692°C. The heat-treatment alters the crystallite size, Lc, from 10.7 to 21.4 Å; the interlayer spacing, d002, from 3.74 to 3.52 Å and the surface area from 0.22 to 1.34 m2/g. ratio ranges from 1.62 to 2.22 and appears to be independent of heat treatment temperature and oxidation level. The surface area of the carbon and its change with oxidation were found to be sensitive to the heat treatment process. Heat treatments at 1000 and 1400°C produce carbon with surface area which increases by nearly two orders of magnitude after 10% oxidation. The oxidation rate decreases with increasing heat treatment temperature with the largest change between 1000 and 1400°C. Samples heat-treated at different temperatures give slightly different activation energies with an average value of 41.5 kcal/mole. 相似文献
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Phenolic resins are important materials in various application sectors due to their outstanding mechanical and thermal properties. However, phenolic resins are known as typical non-graphitized carbon precursor. In this work, important parameters related to the synthesis of PRs were studied: the concentration of the catalyst and the molar ratio between phenol and formaldehyde. The structural information was performed by Fourier Transformation Infrared Spectroscopy and solid state nuclear magnetic resonance of carbon analysis to define mainly between novolac or resol resin. The thermal characteristics of the resins were studied for TGA and their tendencies for graphitization were verified by powder x-ray diffraction and Raman spectroscopy and SEM/HRTEM analysis. As a conclusion, it was verified that the phenolic resins prepared with excess of formaldehyde in acidic medium can present different properties according to their composition, which allows for qualifying them as potential materials for different applications in the technological area that involves graphitized carbon. 相似文献
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Yuchun Jiao Li Xu Huiling Sun Yijie Deng Tao Zhang Guoji Liu 《Journal of Porous Materials》2017,24(6):1565-1574
In this work, nitrogen-doped mesoporous carbon spheres (NMCS) were synthesized through a hard template method by using benzoxazine resin as precursor and ordered mesoporous silica spheres as template. The obtained N-doped mesoporous carbons were amorphous spherical nanoparticles with worm-like mesoporous channels and possessed high surface area of 789 m2/g, large pore volume of 0.49 cm3/g and high nitrogen content of 3.50 wt.%. The adsorption capacity of methyl orange (MO) by NMCS could attain 352.1 mg/g at an optimal condition, while the adsorption capacity of MO by non-doped mesoporous carbon spheres (MCS) was 251.9 mg/g at the same condition. The adsorption process fitted the pseudo-second-order kinetic model and the Langmuir isotherm well. Thermodynamic analysis indicated that the removal of MO by NMCS was spontaneous, endothermic and feasible process. In addition, the adsorption capacity of regenerated adsorbent was 89.04% of the initial level after four regeneration cycles. 相似文献
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Nuran Böke Ziboneni G. Godongwana Leslie F. Petrik 《Journal of Porous Materials》2013,20(5):1153-1161
An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater. 相似文献
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Lei Liao Mingbo Zheng Bin Yan Guangbin Ji Tom Wu Jixuan Zhang Jian Cao 《Carbon》2009,47(7):1841-10995
The microstructures of mesoporous carbon nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, nano-Raman, nitrogen adsorption-desorption and optical transmission. They possessed a high specific surface area 840 m2 g−1 and a 1.07 eV band gap. All mesoporous carbon nanofiber network can act as the channel material in p-type field-effect transistor devices with field-effect mobilities over 10 cm2/V s. Furthermore, mesoporous carbon nanofiber network exhibits better sensitivity and faster response to NO2 gas than that of carbon nanotubes, which makes it a promising candidate as poisonous gas sensing nanodevices. 相似文献
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Mixtures of novolac resin and olive stone biomass in proportions 20 : 80 (w : w) are cured, pyrolyzed up to 1000°C (material C20a), and activated with steam (material C20a). The adsorption properties of these materials and a commercial activated carbon (CC) are investigated based on the adsorption of nitrogen and pentane. The adsorption capacity, the surface area determined by the BET and DRK equation, and the pore volume determined as micropore volume by the DR equation, and as cumpulative pore volume related to the Kelvin equation, for the materials follow the order C20a > CC > C20. The DR equation can be applied for the adsorption of nitrogen on the materials examined in the region of P/Po = 0.005 up to 0.3 that exceeds in both sides the common range for the applicability of the DR equation. The activated materials C20a and CC are mainly microporous and reveal the type I isotherms of the Brunauer classification for nitrogen adsorption. The only pyrolyzed material, C20, contains both micropores and mesopores and reveals characteristics of both types I and II. The number of layers for C20a and CC is lower than 2 and for C20 is more than 2. © 1995 John Wiley & Sons, Inc. 相似文献
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Preparation and characterization of carbon foams derived from aluminosilicate and phenolic resin 总被引:3,自引:0,他引:3
Aluminosilicate-reinforced carbon foams have been prepared by chemical foaming with phenolic resin as matrix precursor and aluminosilicate as the additive. The effects of the amount of aluminosilicate used on the microstructure, mechanical properties and oxidation resistance of the carbon foams have been investigated by scanning electronic microscopy, mechanical testing, and oxidation weight loss, respectively. The results show that the amount of aluminosilicate added has a significant influence on the surface roughness and the structure uniformity of carbon foams. The compressive strengths are usually higher than that of the pure carbon foam sample by as much as 60%. The percentage of weight loss of the carbon foams drops with increasing aluminosilicate content up to 11 wt%, but then increases. 相似文献
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为了解决沸石咪唑酯骨架(ZIF-67)基碳材料比表面积和孔体积较小、氮含量较低、孔径分布不集中的问题,以微米级ZIF-67为模板,引入聚多巴胺(PDA)和三聚氰胺(MA)为共同碳氮前驱体以提升氮掺杂量和调节孔结构,在氢气和氩气的氛围中,利用ZIF-67中钴的自催化作用,经800℃高温一步碳化制备得到钴氮掺杂的中空立方形... 相似文献
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Zhichao Yu Chonghe Xu Kangkang Yuan Xinzhu Gan Haifeng Zhou Xinqiang Wang Luyi Zhu Guanghui Zhang Dong Xu 《Ceramics International》2018,44(8):9454-9462
MgO mesoporous nanofibers were obtained by a template-free electrospinning method. The unique bumpy-structure was obtained on the surface of nanofibers that could enhance the surface area and provide more active sites for adsorption. The formation mechanism of the bumpy-structure has been investigated. The as-prepared MgO nanofibers with a high surface area of 194.17?m2 g?1 exhibited excellent adsorption capacities for fluoride of 237.49?mg?g?1. Furthermore, the MgO nanofibers showed selective adsorption for different organic dyes and have superior adsorption capacity for Congo red (4802.27?mg?g?1). The adsorption processes for both fluoride and Congo red were systematically investigated, which were found to follow the pseudo-second-order kinetic model. By comparison with the reported fabrication routes and adsorption capacities of mesoporous MgO, the synthesis process is simple, controllable and template-free, and the superior adsorption performance provided a potential adsorbent for the removal of fluoride and Congo red in wastewater treatment. The high surface area of the MgO mesoporous nanofibers might also promote its application in basic catalysis and other fields. 相似文献
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A dense, micron-tall layer of carbon nanofibers (CNFs) was grown above a layer of carbon nanotubes (CNTs) during the same synthesis using a thick cobalt catalyst (15 nm). The CNFs had large diameters (100 nm) and were amorphous while the CNTs had small diameter (10–20 nm) and were crystalline. Base growth mechanism was at play for both the nanofibers and the nanotubes. High-resolution transmission electron microscopy characterization suggested that the main mechanisms leading to the growth of the two structures were based on the dewetting of the catalyst layer and its subsequent alloying with the Ta underlayer. We can extend these principles to grow diverse carbon nanostructures during the same synthesis using appropriate multilayer thin films for different applications, especially for electrochemical cells and supercapacitors. 相似文献