JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Yuanjie Wang,Luke Ma,Xueliang Pei,Wanfeng Zhuo,Jing Huang,Qing Huang
The inevitable residual carbon that normally appears in the polycarbosilane-derived SiC ceramics has notorious effects on the crystallinity and thermal conductivity of SiC ceramic. In this study, nano Si was employed to fully exhaust unwanted residual carbon in a liquid polycarbosilane. Through addition of 12 wt% theoretical nano Si and pyrolysis to 1600 °C, the ceramic yield of the liquid polycarbosilane increased from 72.0 wt% to 81.8 wt% and the C/Si ratio of ceramic product decreased from 1.14 to 0.99. Raman spectroscopy and transmission electron microscope also confirmed that the residual carbon almost completely disappeared. In addition, the crystallization ability of SiC also improved, and as a result dramatical improvement in the thermal conductivity of SiC f /SiC composite was achieved. The reaction mechanism was investigated in detail to understand the residual carbon trapping effect of nano Si during the precursor-to-ceramic conversion.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2025
·
IF 5.4
Shurui Xu,Jiaer Li,Bingyu Zhu,Xin Tang,Yujian Li,Linjia Wang,Wenbo Liao,Xiaobo Fu,Hang Chen,Junling Tu,Kailai Zhang,Baizeng Fang,Guoyu Zhong
Investigating renewable, eco-friendly, carbon-based materials with superior electrochemical performance is pivotal for advancing the practical implementation of supercapacitors, yet it presents challenges. In this study, a novel MnO@C-HMT-T composite, consisting of porous carbon-encapsulated MnO, was synthesized from a Mn-hexamine coordinated precursor via an in-situ pyrolysis approach. Among the different materials prepared, the MnO@C-HMT-800 stood out. It displayed a mesoporous architecture with a high specific surface area of 1353.1 m 2 g −1 , which facilitates ion transport and energy storage. Additionally, the MnO encapsulated in the carbon layer enables the generation of pesudocapacitance via the redox reaction of Mn 2+ and Mn 3+ . The interaction between the double-layer capacitance of the porous carbon and the pseudocapacitance of the manganese oxides endows the MnO@C-HMT-T composite with superior electrochemical performance. Consequently, the MnO@C-HMT-800 electrode exhibits an impressive specific capacitance of 575.2 F/g at a current density of 1 A/g, demonstrating exceptional stability at 95.6 % after 10,000 cycles. This surpasses the performance of most reported Mn-based materials in the literature. This work presents an innovative and straightforward process for fabricating carbon-encapsulated transition oxides that could be highly valuable in energy storage systems.
研究领域:
材料科学
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电化学
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能源存储
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纳米材料
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功能材料
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电化学能量储存
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 6
·538
·
IF 3.444
Lili Liu,Xiaojing Zhou,Li Liu,Shuai Jiang,Yingjie Li,Luxia Guo,Shijuan Yan,Xishi Tai
Three bimetallic Cu–Ni nanoparticle-supported catalysts were synthesized by co-immobilization followed by H2reduction. A chromium(III) terephthalate metal organic framework (MIL-101), titanium dioxide (TiO2), and carbon (C) with different properties (acidity and Brunauer–Emmett–Teller surface area) were selected as supports for studying the effect of the support nature on the catalytic activity and selectivity in the oxidation of benzyl alcohol. The physicochemical properties of the Cu–Ni-supported catalysts were characterized by XRD, NH3-TPD, nitrogen adsorption/desorption, TEM, EDS, XPS, and ICP-OES. Bimetallic Cu–Ni nanoparticles were highly dispersed on the support. The catalytic activities of CuNi/MIL-101, CuNi/TiO2, and CuNi/C were tested in the selective oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen under mild reaction conditions. The highest benzaldehyde yields were achieved with CuNi/TiO2, CuNi/MIL-101, and CuNi/C catalysts at 100 °C within 4 h under 5, 3, and 3 bar of O2, respectively. The bimetallic Cu–Ni-supported catalysts possessed two types of catalytic active sites: acid sites and bimetallic Cu–Ni nanoparticles. The CuNi/MIL-101 catalyst possessed a high number of acid sites and exhibited high yield during selective benzyl alcohol oxidation to benzaldehyde. Importantly, the catalysts exhibited a high functional group (electron-donating and electron-withdrawing groups) tolerance. Cu–Ni-supported catalysts with an Cu:Ni mole ratio of 1:1 exhibited the highest yield of 47% for the selective oxidation of benzyl alcohol to benzaldehyde. Reusability and leaching experiment results exhibited that CuNi/MIL-101 showed better stability than CuNi/TiO2and CuNi/C catalysts due to the large porous cavities of MIL-101 support; these cavities can be used to trap bimetallic Cu–Ni nanoparticles and inhibit nanoparticle leaching.Keywords:Cu–Ni nanoparticles;MIL-101;TiO2;carbon;benzyl alcohol oxidation
研究领域:
催化
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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
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Jiamin Huang,Guanghui Zhang,Jie Zhu,Mingrui Wang,Fanshu Ding,Chunshan Song,Xinwen Guo
The catalytic conversion of CO2 to higher alcohols (HAs, representing ethanol and alcohols with more than two carbon atoms) has been of great interest to mitigating the greenhouse effect and effectively utilizing CO2. However, most present catalysts have disadvantages of poor activity (conversion less than 30%) and selectivity (less than 10%) and high price. Herein, we report a Mn- and K-modified iron carbide catalyst that offers a CO2 conversion higher than 40% and a selectivity of higher alcohols exceeding 10%, and the proportion of propanol and butanol in alcohol products is more than 30%. Unpromoted iron carbide has a strong ability of hydrocarbon chain growth, leading to the fast formation of hydrocarbon products rather than HAs. However, on the Mn- and K-modified iron carbide catalyst, K is used to increase the surface C/H ratio of the catalyst by enhancing the adsorption of CO2 on the catalytic surface. The increased C/H ratio is indispensable to the formation of HAs, and the addition of Mn promoter dramatically improves the production of HAs, especially the formation of propanol and butanol. The synergistic effect between Mn and K on iron carbide is the key to produce HAs. In addition, the Mn- and K-modified iron carbide is of low cost, which can potentially provide an alternative for the hydrogenation of CO2 to produce valuable chemicals.
研究领域:
催化化学
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环境科学
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能源科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Jie Dang,Yijie Wu,Zepeng Lv,Xuewei Lv
Tungsten carbides , which can be widely used as cutting and drilling tools, chemical catalysts and aerospace coatings, have attracted widespread attentions. The present work reported a simple method to prepare tungsten carbides by using WO 2 as the raw materials and CO as the reduction and carbonization agent. It was found that at lower and moderate temperatures, all the final product was WC, while at higher temperatures, the final products were W 2 C or W. The reduction and carbonization mechanism was also studied theoretically and experimentally. WO 2 was reduced and carburized to WC in one step at lower temperatures; WO 2 was first reduced and carburized to W 2 C and then to WC at moderate temperatures; while at higher temperatures, WO 2 was first reduced to metallic W and then carbonized to WC or W 2 C, but with the temperature increasing, the carbonization became difficult and required much higher CO content.
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
CARBON
·
2023
·
IF 10.9
Ruijia Wang,Jianyong Wan,Hongda Guo,Bing Tian,Shujun Li,Jian Li,Shouxin Liu,Tony D. James,Zhijun Chen
Converting CO 2 with various epoxides to cyclic carbonates is extremely important. However, most of catalysts for such conversion either require complicated fabrication or are obtained from unsustainable sources. Motivated by this problem, we prepare biomass-based “all-in-one” carbon dots as nano-organocatalysts for firstly converting CO 2 to cyclic carbonates. In this work, carbon dots (CD@KI) with high catalytic performance and good recyclability are prepared from sodium phytate (SP), polyethylenimine (PEI) and KI using one-pot hydrothermal treatment featuring cheap precursors and simple operation. Assisted by highly catalytic activity of CD@KI, up to 99.5% yield is achieved for converting CO 2 and various epoxides to cyclic carbonates under mild conditions (solvent-free and 1 atm of CO 2 ). Moreover, the conversion yield is maintained for reactions up to 10 g in scale. Significantly, by taking advantage of the inherent luminescence of CD@KI, the as-formed cyclic carbonates catalysed by CD@KI can be directly converted to afterglow polymer composites .
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2020
·
IF 14.588
Tao Liang,Enshan Liu,Minghui Li,Elena V. Ushakova,Stephen V. Kershaw,Andrey L. Rogach,Zikang Tang,Songnan Qu
In this work, we report a successful extension of the family of light-emitting colloidal carbon nanostructures to a number of different shapes and morphologies, namely, carbon nanorolls (CNRs) and carbon nanobelts (CNBs). Near infrared (NIR)-emissive CNRs were synthesized via a solvothermal fusion of carbon dots (CDs) triggered by a dehydration process of their surface functional groups. They appear in a form of short cylinders, with diameters ranging from 20 to 40 nm and cylinder lengths ranging from 7 to 20 nm. In ethanol solution, CNRs have a maximum absorption peak at 665 nm and a NIR emission band extending from 650 to 800 nm, with a photoluminescence quantum yield of 9.2%. Intriguingly, the rolled structure of CNRs can be uncoiled under 655 nm laser irradiation (power density 1 W·cm–2) of their solution in ethanol, forming CNBs with a width of 7–20 nm and lengths reaching several hundreds of nanometers, which is accompanied by a considerably decreased absorption band at 665 nm and a decreased NIR emission. This unfolding is ascribed to the decrease of the strength of interlayer hydrogen bonding, owing to the photothermally induced dehydration and further carbonization of the CNRs. Alongside the decreased NIR emission, CNBs exhibit enhanced green and red emissions under UV and green light excitation, respectively, which allows us to demonstrate multiple-level luminescence encryptions on a paper stamped with CNR- and CNB-inks.
研究领域:
材料科学
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化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Xiao Sun,Chuanbing Cheng,Jianxing Shen,Yang Liu,Tailin Wang,Qian Ma,Runhua Fan
In this work, amorphous carbon/alumina (C/Al 2 O 3 ) metacomposites with tunable negative permittivity were synthesized by a facile impregnation method. We analyzed the influence of carbon content and the carbonization temperature on the microstructure and electrical properties of the metacomposites. It was found that the conductive carbon networks were formed in the composites with the higher carbon contents and carbonization temperatures, which lead to the appearance of a metal-like conduction and negative permittivity behavior. Low-frequency plasmonic state provided by plenty of free electrons in the carbon networks resulted in the negative permittivity, and its numerical values could be effectively adjusted by controlling the carbon content and carbonization temperature, which could be well explained by Drude model. This work provides a feasible way to prepare metacomposites with tunable negative permittivity, which will expand their potential applications in shielding, absorbing and novel capacitor fields.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2022
·Vol. 12
·期 5
·479
·
IF 4.501
Xiangxiang Li,Shuling Chang,Yanting Wang,Lihong Zhang
The selective and effective conversion of CO2into available chemicals by electrochemical methods was applied as a promising way to mitigate the environment and energy crisis. Metal silver is regarded as an efficient electrocatalyst that can selectively convert CO2into CO at room temperature. In this paper, a series of coral-like porous Ag (CD-Ag) catalysts were fabricated by calcining silver-carbonaceous microsphere (Ag/CM) precursors with different Ag content and the formation mechanism of CD-Ag catalysts was proposed involving the Ag precursor reduction and CM oxidation. In the selective electrocatalytic reduction of CO2to CO, the catalyst 15 CD-Ag showed a stable current density at −6.3 mA/cm2with a Faraday efficiency (FE) of ca. 90% for CO production over 5 h in −0.95 V vs. RHE. The excellent performance of the 15 CD-Ag catalysts is ascribed to the special surface chemical state and the particular nano-coral porous structure with uniformly distributed Ag particles and pore structure, which can enhance the electrochemical active surface areas (ECSA) and provide more active sites and porosity compared with other CD-Ag catalysts and even Ag foil.Keywords:carbon dioxide reduction;silver;carbonaceous microsphere;carbon monoxide;electrochemical
研究领域:
环境科学
·
材料科学
·
电化学工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2023
·
IF 5.2
Qiang Wang,Yaru Li,Zichen Yu,Xuewen Li,Shouhua Yin,Wen Ji,Yonghua Hu,Weiping Cai,Xianbiao Wang
Highly porous carbon adsorbent is much desired to diminish greenhouse effect caused by CO 2 emission and benefit for subsequent carbon cycle . Herein, a low-cost and environment-friendly carbonization strategy was reported for preparation of highly porous carbon derived from biomass. Such carbonization is a synergistic process with hydrothermal treatment coupled with a subsequent pyrolysis using sugarcane as biomass. The obtained hydrothermal-pyrolysis derived porous carbon (HPC) has a BET surface area of 938 m 2 /g, which is much higher than that of carbon produced through direct pyrolysis (PC, 528 m 2 /g). During the hydrothermal carbonization pretreatment, highly thermostable aromatic skeletons are formed and converted to carbon skeletons in the post-pyrolysis process, leading to formation of highly stable micropores and higher surface area. Further, HPC shows remarkable adsorption ability of CO 2 (2.8 mmol/g, 25 °C, 1 bar), higher than that of PC (2.1 mmol/g). In addition, the HPC exhibits high CO 2 /N 2 adsorption selectivity and recyclability, demonstrating its potential application in CO 2 capture. This work not only gives new light for tailoring carbon materials with highly porous structure but also provides novel adsorbent for CO 2 adsorption.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
KEY ENGINEERING MATERIALS
·
2014
·
IF 0
Jin Jia,Yuan Yuan Zhu,Ya Fei Zhang,Ruo Yu Chen,Bao Lin Xing,Ai Guo Zhou
Carbide-derived carbons (CDCs) are produced from carbides by removing non-carbon elements in the process of selective etching. In this paper, CDC was prepared from TiC by chlorination at the temperature range of 600~1100°C. In the chlorinating process, carbide-derived carbon with different microstructure was obtained by controlling the reaction temperature. The structures of CDC were revealed with X-ray diffraction and Raman spectroscopy. The morphologies of CDC were analyzed by scanning electron microscope. From X-ray diffraction analysis, the CDC obtained from TiC in this experiment mainly consisted of amorphous carbon. Basing on scanning electron microscopy, carbide-derived carbon from TiC maintained the shape and size of TiC particles. Keywords: Carbide-derived carbons; chlorination; TiC
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
Small
·
2019
·Vol. 15
·期 44
·1902819
·
IF 10.856
Xiaojun Ruan,Jiangjiang Luo,Rui Wang,Yanbo Yao,Jingjiao Guan,Tao Liu
A nanometer-thick carbon film with a highly ordered pattern structure is very useful in a variety of applications. However, its large-scale, high-throughput, and low-cost fabrication is still a great challenge. Herein, microcontact printing (µCP) and direct laser writing carbonization (DLWc) are combined to develop a novel method that enables ease of fabrication of nanometer-thick and regularly patterned carbon disk arrays (CDAs) and holey carbon films (HCFs) from a pyromellitic dianhydride-oxydianiline-based polyamic acid (PAA) solution. The effect of PAA concentration and pillar lattice structure of the polydimethyl siloxane stamp are systematically studied for their influence on the geometrical parameter, surface morphology, and chemical structure of the finally achieved CDAs and HCFs. Within the PAA concentration being investigated, the averaged thickness of CDAs and HCFs can be tailored in a range from a few tens to a few hundred of nanometers. The µCP+DLWc-enabled electrically conductive CDAs and HCFs possess the characteristics of ease-of-fabrication, nanometer-thickness, highly regular and controlled patterns and structures, and the ability to form on both hard and soft substrates, which imparts usefulness in electronics, photonics, energy storage, catalysis, tissue engineering, as well as physical, chemical, and bio-sensing applications.
研究领域:
材料科学
·
纳米科技
·
生物医学工程
·
表面化学
·
微纳加工
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）