PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2019
·Vol. 21
·期 32
·17801-17810
·
IF 3.567
Qiushi Song,Zheng Zhang,Hongwei Xie,Huayi Yin,Zhiqiang Ning
The carbonization of transition metals in molten salts was performed to study the effect of electrochemical polarization and molten salt medium on the carbonization process. The carbonization of niobium (Nb) has been systemically investigated in Ar atmosphere and molten salts. The effect of particle size and structure of the starting materials, molten salt medium, and electric field on the formation of NbC was studied to reveal the dynamic barriers in the carbonization process. A native oxide layer and/or niobate derivatives generated on the Nb particles are the main barriers for the mass transfer of carbon and Nb towards each other. The results showed that molten salts can accelerate the formation of NbC by enhancing the diffusion of carbon, and the kinetic barrier can be effectively eliminated by supplying negative polarization to the cathode in molten salts to remove the oxide barriers, thereby enhancing carbonization. Besides Nb, tungsten (W), molybdenum (Mo), titanium (Ti), and tantalum (Ta) can also be carbonized in molten salts with the assistance of an applied electric field.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2024
·
IF 3.7
Huijun Shang,Hengli Li,Weijun Li,Feng Pan,Zhan Du
In this paper, the effects of reaction parameters on the deep-reduction and carbonization process of WO 2 -Co to WC-Co were studied. The results indicate that oxygen loss rate of WO 2 is positively correlated with temperature and methane partial pressure. The partial pressure of methane has no significant effect on the formation rate of WC. The carbon content and particle size of the product increase with the increase of CH 4 partial pressure. By synergistically regulating the reaction temperature to 950 °C, methane partial pressure to 1.25%, and reaction time to 60 min, ultrafine WC-Co powder without η phase can be obtained. The particle size of the composite powder is 128 nm, with total carbon content of 6.16%, free carbon content of 0.4%, and residual oxygen content of 0.05%, respectively. The growth rate relationship of tungsten carbide is as follows:
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
Polymers
·
2024
·Vol. 16
·期 8
·1160
·
IF 4.7
Ahmed Elhassan,Xiaoshuang Lv,Ibrahim Abdalla,Jianyong Yu,Zhaoling Li,Bin Ding
Ever-increasing electromagnetic pollution largely affects human health, sensitive electronic equipment, and even military security, but current strategies used for developing functional attenuation materials cannot be achieved in a facile and cost-effective way. Here, a unique core-shell-like composite was successfully synthesized by a simple chemical approach and a rapid microwave-assisted carbonization process. The obtained composites show exceptional electromagnetic wave absorption (EMWA) properties, including a wide effective absorption band (EAB) of 4.64 GHz and a minimum reflection loss (RLmin) of −26 dB at 1.6 mm. The excellent performance can be attributed to the synergistic effects of conductive loss, dielectric loss, magnetic loss, and multiple reflection loss within the graphene-based core–shell-like composite. This work demonstrates a convenient, rapid, eco-friendly, and cost-effective method for synthesizing high-performance microwave absorption materials (MAMs).
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Surfaces and Interfaces
·
2025
·
IF 6.3
Jun Sun,Bo Ran,Ping Hu,Jialu Fang,Qihua Sun,Zhaofeng Wu,Haiming Duan
For the first time, egg custard, typically considered a potential carbon material, was transformed into gas-sensing materials using an eco-friendly, inexpensive, and straightforward carbonization process. Detailed examination proved that the carbonized egg custard at 600 °C exhibited a hollow configuration with nanoscale pores, greatly enhancing the surface area for gas adsorption. Furthermore, heteroatoms self-doped biomass-derived carbon materials can offer a plentiful supply of reactive sites and modify the material's shape to facilitate gas adsorption. The carbonized egg custard sensor showed good selectivity, repeatability, and a moderate response-recovery cycle to NH 3 . Density functional theory calculations further confirmed that doping with trace heteroatoms enhances the adsorption of O 2 and NH 3 molecules. This work provides a novel and sustainable approach for converting egg custard into biomass-derived carbon materials with promising gas-sensing applications.
研究领域:
材料科学
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Wei Gao,Zhenyu Wang,Yongzheng Zhang,Chunyin Shen,Yanli Wang,Liang Zhan
Phenolic aerogels have addressed considerate application in fabricating lightweight ablative materials owing to their excellent characteristics of large surface area, low bulk density, and low thermal conductivity . However, unsatisfactory thermal stability still limits their extensive applications. To enhance the thermal stability, we reported a facile co-precursor strategy to prepare boron-modified phenolic aerogels, through sol–gel polymerization of phenylboronic acid and phenolic resin. The thermal stability of hybrid aerogels is remarkably enhanced, achieving a char yield of up to 64.16 % at 850 ℃ due to the much higher bonding energy of B-O bonds. The phenyl-borates structure gradually transferred into B 2 O 3 , effectively fixing the oxygen content and reducing the carbon loss during the carbonization process. Moreover, the in-situ formed phenyl-borates structure contributes to forming a denser network, which affords the hybrid aerogels with diverse properties: low density (0.31–0.34 g/cm 3 ), a hierarchical micro- meso -macro porous structure with small particle size (28.42–48.58 nm), promoted compressive strength (20.65–28.46 MPa), and excellent insulation performance (0.0406–0.0564 W/(m•k)). These integrated superiorities enable the boron-modified phenolic aerogels to perform effectively in thermal insulation fields, especially for aerospace related industry.
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
CONSTRUCTION AND BUILDING MATERIALS
·
2021
·
IF 6.141
Xiaoliang Fang,Dongxing Xuan,Baojian Zhan,Weifeng Li,Chi Sun Poon
In a previous study, a novel two-step carbonation technique was developed to convert finely crushed hardened cement paste into a calcium-rich and a silica-rich residue. This paper reports a further work on optimizing the two-step carbonation process by studying the influences of a series of experimental variables including particle size, Na 2 CO 3 concentration, reaction time and temperature, CO 2 flow-rate, and CO 2 concentration on the carbonation processes. The characteristics of the chemical and physical properties of calcium-rich (mainly calcite) and silica-rich (silica and alumina-silica gel) residues formed were analyzed by using X-ray fluorescence (XRF), powdered X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). It was found that the changes in the experimental variables of both Steps 1 and 2 mainly affected the amounts of new products formed, but only slightly changed the chemical structures of the new products. Through a series of comparative tests, the most efficient conditions for the two-step carbonation process was reported. Comparing to the previous exploratory reaction conditions of 24 h stirring and 7 h flow-through carbonation using pure CO 2 gas, the optimum conditions would be: i) in Step 1: a 5–10 wt% Na 2 CO 3 solution, a reaction duration of 5–7 h under ambient temperature, ii) in Step 2: a CO 2 gas with a concentration of>50%, and the carbonation ending with a final pH ≤ 9.8 in less than 90 mins. Meanwhile, the estimated CO 2 uptake in Step 2 was 0.136 g per gram of RCP. In addition, the supernatant of Step 2 after centrifugation can be recycled and reused as the Na 2 CO 3 solution in Step 1 for another reaction cycle after pH adjustment by NaOH.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
CARBON
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2021
·
IF 9.594
Gaoxu Han,Jianbo Jia,Quanrun Liu,Guangxu Huang,Baolin Xing,Chuanxiang Zhang,Yijun Cao
A series of coal-based hierarchical porous carbons with adjustable pores were successfully prepared with the assistance of the soluble salt Zinc chloride (ZnCl 2 ). During the carbonization process , ZnCl 2 , with a low melting point (238 °C), “in situ occupied” and “occupied” within the coal solids to generate interconnected pores, which acted as a template. Simultaneously, the activation of ZnCl 2 reduced the oxygen content of products and further improves their electrical conductivity . Optimization of the mass of the salt and the carbonization temperature resulted in targeted product with a suitable specific surface area (1581 m 2 g −1 ) and unique pores (V meso /V total = 45%), which exhibited a high specific capacitance (470.7 F g −1 at 0.5 A g −1 ) in 6 M KOH electrolyte. The symmetrical supercapacitor of targeted product has favorable rate performance (256.7 F g −1 at 0.5 A g −1 , 84.8% capacity retention at 30 A g −1 ) and excellent cycling performance (after 10000 cycles, the specific capacitance increases to 115% of the initial capacity at 10 A g −1 ). In the EMIMBF 4 electrolyte system, the energy density is 95.31 Wh kg −1 at 213.13 W kg −1 . Therefore, this work provides an effective method to improve the green and efficient use of coal.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Jian Rong,Fengxian Qiu,Tao Zhang,Yao Zhu,Jicheng Xu,Qing Guo,Xiaoming Peng
Metal-organic framework (MOF) materials have exhibited a wide range of application as heterogeneous catalyst or catalyst precursor. However, the catalytic activity of many micro-sized or big block MOFs usually was limited by mass transfer resistance and low percentage of exposed active site. Herein, we report a novel strategy to prepare high-efficiency non-noble metal nanocatalysts via the exfoliation of stromatolithic MOF crystal combined subsequent carbonization process. First, micro-sized Cu- or Zn-containing MOF (Cu- or Zn-MOF) was synthesized by the coordination bonds between metal ion precursor and organic ligand. Subsequently, an exfoliated process was carried out to harvest MOFs nanosheets by H 3 PO 4 molecules selective diffusion and etching between the MOFs crystal layer. Cu or Zn nanoparticles embedded by porous carbon (Cu@C or Zn@C) was finally obtained by the carbonization of Cu-MOF or Zn-MOF nanosheets in N 2 atmosphere, respectively. Cu@C and Zn@C nanosheets showed excellent catalytic activity and reusability toward the reduction of 4-nitrophenol and organic dyes. Such enhanced performance could be attributed to the high specific surface area, good dispersibility, fully exposed active sites, and the synergistic effect of metal NPs and carbon. The strategy presented herein can give MOFs great potential for application in the treatment of environmental wastewater.
研究领域:
材料科学
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环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
ENERGY
·
2024
·
IF 9
Qiang Hu,Han Zhang,Qiaoting Mao,Jinjiao Zhu,Shihong Zhang,Haiping Yang,Hanping Chen
While numerous research studies have delved into the co-pyrolysis of biomass and plastic waste, limited attention has been devoted to comprehending the interaction mechanism that impacts biomass deoxygenation and carbonization. Therefore, this study explores the co-effect of temperature and polypropylene blending ratio on co-pyrolysis reaction kinetics, distribution of oxygenates/hydrocarbons, as well as the evolution of biochar structure. At a blending ratio of 0.5, the co-pyrolysis exhibits the lowest activation energy (146 kJ/mol), approximately 25.1 % lower than that required for individual pyrolysis . The interaction between bamboo waste with polypropylene increases the O-abstraction process, resulting in the creation of O-containing free radicals and hydrocarbon compounds. The peak proportion of aromatic compounds, reaching approximately 69.5 %, is observed at 700 °C when the blending ratio is 0.5. The H-abstraction process converts large-molecular alkanes into H free radicals and tiny-molecular unsaturated hydrocarbons. The aliphatic functional group content diminishes as the polypropylene ratio increases. The maximum specific surface area (7.70 m 2 /g) and pore volume (21.7 mm 3 /g) are achieved at a blending ratio of 0.75. Notably, polypropylene exerts minimal influence on the graphite crystallite size and graphitization degree of biochar. This research significantly contributes to advancing our understanding of the interaction mechanisms between biomass and plastic waste.
研究领域:
能源与燃料
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环境科学
·
生物质转化
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 54
·期 2
·1539-1548
·
IF 2.993
Wang Chao,Ping Hang
Biomineralization-associated proteins are responsible for the structure-forming process of biominerals. Aiming to regulate the synthesis of nanostructured TiO 2 anatase, an artificial protein 5R5 derived from silaffins was displayed on Escherichia coli surface through genetic manipulation. The genetically modified bacterial cells serve as the framework for the formation of rod-shaped TiO 2 , assembled by nanoparticles, as well as provide a carbon source in situ during the carbonization process. The particle size and carbon content were controllable by changing the heating temperature and time. The electrode annealed at 800 °C for 1 h shows the highest reversible capacity of 160.2 mA h g −1 after 200 cycles at a current rate of 1C. This unique nanostructured anatase not only shortens the diffusion pathway of lithium ions and electrons, but also improves the electric conductivity and tolerates the volume change during charging/discharging owing to carbon coating. However, the larger particle size and high carbon content were not advantageous to improve lithium storage performance.
研究领域:
材料科学
·
生物化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2022
·
IF 9.463
Sinan Zheng,Zhihui Zeng,Jing Qiao,Yue Liu,Jiurong Liu
The C/MnO/Co nanocomposite fibers were prepared via a facile electrospinning and subsequent carbonization process. Co acting as the magnetic nanoparticles and MnO nanoparticles serving as impedance modulator were introduced, effectively inhibiting the agglomeration of carbon fibers during annealing. This optimizes the microstructure and significantly improves the microwave absorption performance of the nanocomposites with diameters of 250–350 nm and rough surface morphologies . The nanocomposite fibers with equal MnO and Co molar contents exhibited the minimum reflection loss of − 71.7 dB at a frequency of 14.1 GHz and an absorber thickness of 2.3 mm, and the effective absorption bandwidth reached at 6.3 GHz at a thickness of 2.6 mm. The high microwave absorption performance can be attributed to the synergistic coactions of conduction loss, magnetic loss, interfacial polarization, and multiple scatterings derived from the rational design of the constituents and microstructure of the nanocomposites.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Qihao Tang,Ge Chu,Yishun Xie,Chengmi Yang,Fangzhou Tang,Ziwei Li,Shaorong Lu,Lin Qin,Zhewei Yang,Xin Fan
Lithium-ion capacitors (LICs) combine the advantages of lithium-ion batteries and supercapacitors, demonstrating great application prospects in the fields of large-scale renewable energy, and have been attracting increasing attention. Regrettably, the power capability of LICs is significantly hindered by the incongruent kinetics between battery-type anodes and capacitive cathodes. To address this challenge, in this study, a carbon anode derived from Zn/Co bimetallic metal-organic framework (MOF), specifically the Zn 80 Co 20 -PC, is synthesized through a direct carbonization process. Benefitting from the optimal degree of graphitization, substantial specific surface area, and comprehensive porous structure, the incongruent behaviour is effectively alleviated. As a result, the battery assembled with Zn 80 Co 20 -PC yielded an impressive capacity of 397.1 mAh g −1 at a current density of 0.1 A g −1 and a commendable rate capability of 109.6 mAh g −1 at 1.6 A g −1 . Moreover, the LICs crafted with a pre-lithiated Zn 80 Co 20 -PC anode and an activated carbon (AC) cathode (designated as Zn 80 Co 20 -PC//AC LICs) exhibit a notable energy density of 123 Wh kg −1 and an elevated power density of 7150.3 W kg −1 , maintaining exceptional durability through 5000 cycles. This study introduces innovative strategies for integrating advanced anode materials into lithium-ion capacitors.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）