CARBON
·
2021
·
IF 9.594
Na Yang,Rong Shao,Zhengping Zhang,Meiling Dou,Jin Niu,Feng Wang
Gelatin, a natural macromolecular substance formed by the hydrolysis of collagen, offers the advantages of abundant resources and low cost. It is a good precursor for the synthesis of N, O-doped carbon materials. Although some gelatin-derived carbon materials have been used for electrochemical energy storage , there have been few studies for the mechanism of gelatin carbonization . In addition, the influence of heteroatoms and defects on the K-ion storage performance remains unclear. In this work, in situ and ex situ characterization methods have been used to study the mechanism of gelatin carbonization. The pathways leading to formation of the carbon framework, heteroatom doping and defect generation in gelatin-based carbons during the pyrolysis process have been clearly identified. Moreover, by means of DFT calculations and experimental measurements, it has been confirmed that heteroatoms and defects both play important roles in improving the storage performance of potassium ions. By virtue of its abundance of both heteroatoms and defects, our optimized anode shows better electrochemical performance than graphite anodes. This study not only clarifies our understanding of carbonization mechanism and mechanism of K-ion storage in carbon materials, but also provides pathways for the synthesis and applications of new carbon-based anode materials for alkali-ion batteries.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
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
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Zhongyu Yang,Long Zhang,Yiyuan Zhang,Mengyuan Bai,Yunchuan Zhang,Zihan Yue,Erhong Duan
Pyrolysis process of metal-organic frameworks (MOFs) was analyzed by thermal analysis kinetics for the study of the synthesis of MOFs-based carbon materials with high adsorption performance. The process was studied based on the thermogravimetric mass spectrometry (TG-MS), through which the gas products of the pyrolysis process were detected. The HKUST-1 and MIL-101 were prepared by solvothermal method and characterized by XRD, BET, SEM and TEM. The characterization results showed that HKUST-1 and MIL-101 have been successfully prepared with cubic octahedral morphology and specific surface areas up to 1477.50 m 2 /g and 2239.88 m 2 /g, respectively. The data of TG-DTG showed that the pyrolysis of HKUST-1 and MIL-101 could be divided into three stages and seven stages, respectively. The kinetic triplets of different pyrolysis stages were calculated by iso-conversional methods, and the gas products decomposed were analyzed, through which the pyrolysis mechanism of MOFs was inferred. The first pyrolysis stages of HKUST-1 and MIL-101 were both dehydration stages, the E values of both were less than 100 kJ/mol, and the pyrolysis mechanism of both two materials at this stage were the chemical reaction mechanism. The average apparent activation energy of the main pyrolysis carbonization stages of both was about 180 kJ/mol, and both followed the random nucleation and subsequent growth mechanism, indicating that there were some uniformities between the two materials in the main pyrolysis stage. The main gas products in this stage were CO, CO 2 and benzene. The apparent activation energy of the final deep carbonization stage were 564.36 and 387.60 kJ/mol, respectively, and mechanisms followed were chemical reactions and three-dimensional diffusion mechanisms, meaning that there were some differences between the two materials in the deepening stage.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CEMENT AND CONCRETE RESEARCH
·
2024
·
IF 10.9
Miao Ren,Peiliang Shen,Yong Tao,Chi-sun Poon
Carbonation of calcium silicate (CS) minerals to produce hardened construction materials has attracted increasing interest, but the efficiency of conventional CS minerals is low. This study prepared a highly reactive β-C 2 S derived from a C-S-H precursor through hydrothermal synthesis . The potential CO 2 uptake ability, product compositions, microstructural characteristics , and carbonation mechanisms of the hydrothermal β-C 2 S were investigated. The results showed that the hydrothermal β-C 2 S achieved 3.7 times higher carbonation efficiency compared to the reference β-C 2 S prepared by traditional calcination and reached a carbonation degree of 56.1 % within 10 min. Its high reactivity was attributed to large specific surface area, unique thin lath structure, and fine grain size . The novel type of C-S-H produced, special thin lath structure evolution and sufficient ACC led to an almost complete carbonation degree of hydrothermal β-C 2 S. The developed carbonation process could be used to valorize recycled concrete waste which contains a large amount of C-S-H.
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
Gels
·
2022
·Vol. 8
·期 5
·308
·
IF 4.432
Zixuan Zheng,Guojie Liang,Li Li,Jing Liu,Xinbo Wang,Yi Sun,Kai Li
The weak inherent non-covalent interactions between carbon aerogel backbone nanoparticles obtained by the pyrolysis of conventional organic aerogel can lead to poor mechanical properties. When applied in the thermal protection system of a high-speed spacecraft, the preparation of carbon aerogel insulation materials with excellent formability and high mechanical strength still remains a huge challenge. This work reports an efficient approach for fabricating carbon foam-reinforced carbon aerogel composites by compounding the nanoporous polyimide aerogel into the microporous pre-carbonized phenolic resin-based carbon foam via vacuum impregnation, gelatinizing and co-carbonization. Benefiting from the co-shrinkage caused by co−carbonization, the thermal insulation capacity of the carbon aerogel and the formability of the pre−carbonized foam are efficiently utilized. The shrinkage, density and carbon yield of aerogels, pre-carbonized foams and the composites at different temperatures were measured to analyze the formation of the interfacial gap within the composite. The co-carbonization mechanism of the polyimide aerogels and phenolic resin-based pre-carbonized foams was analyzed through XPS, TG-MS, and FT-IR. Among the prepared samples, CF30-CPI-1000 °C with small interfacial gaps showed the lowest thermal conductivity, which was as low as 0.56 W/(m·K) at 1900 °C, and the corresponding compressive strength and elastic modulus were as high as 0.532 MPa and 9.091 MPa, respectively.Keywords:polyimide aerogel;carbon aerogel;thermal conductivity;shrinkage;co-carbonization mechanism
研究领域:
材料科学
·
航空航天工程
·
隔热材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Mengyu Dou,Yan Qiao,Xu Hu,Hengyang Miao,Ligong Zhou,Xuekuan Li,Xianglin Hou,Yingxiong Wang,Mingxing Tang
The poor textural properties of initial biochar materials have hindered their extensively applied as catalyst supports. Herein, cellulose biochar materials with the gradient porous and high specific surface area were synthesized by adding different ratios of ZnCl 2 , and as supports to prepare Pd/C cel catalysts for efficient maleic acid hydrogenation in water. The characterization results indicated that the textural propertiesand dispersion of Pd in Pd/C cel catalysts depended on the ratio of ZnCl 2 to cellulose. The Pd/C cel ZnCl 2(1:3) catalyst exhibited the best catalytic activity among all catalysts and outstanding stability for reusing 8 times under mild conditions (60 °C, 2 MPa). In addition, this synthesis strategy was also suitable for other biomass materials (glucose, sucrose, and starch) and the catalytic performance of ZnCl 2 -modified Pd/C catalysts in maleic acid hydrogenation reaction also improved dramatically. The carbonization mechanism was discussed by TG-MS and the results illustrated that ZnCl 2 reduced the carbonization temperature and altered the pyrolysis behavior of biochar as a result of excellent catalytic behavior. This work provided a facile and universal strategy for synthesizing biochar high-efficient supported catalysts with gradient porous structure and high specific surface area.
研究领域:
催化
·
材料科学
·
化学工程
·
环境科学
✓ 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）