JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Meiqi Mu,Jing Yu,Zhiqian Yao,Suqiong Xu,Chuicai Rong,Xianke Zhang,Zuzhou Xiong,Xingquan Wang,Xiaokang Li,Jujun Yuan
CeO 2 /Co/C composites have been successfully prepared by a template method. When being applied as electromagnetic (EM) wave absorbers, CeO 2 /Co/C composites exhibit stronger EM wave absorption properties than Co/C and CeO 2 /C composites. The enhanced performance can be attributed to the unique structures of CeO 2 /Co/C composites, in which the synergistic effect of conductance loss, polarization loss together with magnetic loss play an important role for improving the EM wave absorption properties. Additionally, the CeO 2 /Co/C composites own more heterogeneous interfaces and high porosity, which promotes the continuous occurrence of interface polarization and dipole polarization, resulting in increased multiple scattering. The CeO 2 /Co/C composites show a RL min of − 55.02 dB and an EAB of 3.29 GHz at the matching thickness of 2.82 mm. This work provides an effective strategy for constructing CeO 2 /Co/C composites for microwave absorbing material with high performances.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Huihuang Shen,Changdong Ju,Junjun Wang,Huabo Huang,Jiayou Ji,Liang Li
There is a challenge to boost the electromagnetic wave absorption performance of magnetic carbon-based materials by rationally adjusting the structure of MOF. In this paper, nanoclip-shaped polypyrrole (PPy) was wrapped on the surface of the Co/C nanoparticle derived from Co-MOF via in-situ polymerization of pyrrole with the help of cetylammonium bromide. The electromagnetic parameters of prepared Co/C@PPy can be easily tuned by adjusting the feed ratio of PPy to Co/C. The optimum value of reflection loss (RL) for Co/C@PPy is −45.49 dB at 2.4 mm and 15.12 GHz when the feed ratio of pyrrole to Co/C is 200 μL to 80 mg, and the effective absorption bandwidth (EAB, RL ≤ −10 dB) reaches 5.97 GHz (11.76–17.73 GHz) at the matching thickness of 2.5 mm. This study paves the way for further design and preparation of the nanocomposites based on MOF-derived nanostructures with excellent EMW absorption performance.
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 Science and Engineering B-Advanced Functional Solid-State Materials
·
2025
·
IF 4.6
Feng Hu,Jing Li,Xiaoling Peng,Shan Tao,Jingcai Xu,Bo Hong,Xinqing Wang
In this study, the novel Co/C/LaFeO 3 composites were synthesized by in-situ growth of LaFeO 3 on Co/C derived from ZIF-67. The electromagnetic wave (EMW) absorption performance of the Co/C/LaFeO 3 composites was investigated with varying proportions of Co/C and LaFeO 3 . When the weight ration of Co/C to LaFeO 3 was 2:1, the Co/C/LaFeO 3 composites exhibited a remarkable minimum reflection loss (RL min ) of −57.8 dB and demonstrated an effectively absorbing broadband (EAB, RL min ≤ -10 dB) of 5.12 GHz at 1.7 mm. Benefiting from the combined impact of Co nanoparticles, carbon layer, and LaFeO 3 , diverse interfaces and conductive networks were formed, and optimized impedance matching was obtained. In addition, the incorporation of LaFeO 3 significantly enriched the electromagnetic loss mechanisms, ultimately enhancing the comprehensive EMW absorption efficiency of the Co/C/LaFeO 3 composites. This research serves as an essential guide for designing and synthesizing MOF-derived carbon composites with significant EMW absorption capacities.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Qian Ma,Rong Qiang,Yulong Shao,Xiao Yang,Rui Xue,Bowen Chen,Yi Chen,Shijiang Feng
The demand of microwave absorption materials (MAMs) with unique morphologies and electromagnetic (EM) balance has become necessary in recent years. Due to the ease of synthesis and tunable structure, metal–organic frameworks (MOFs) are widely used for this special MAMs. In this study, a new three-dimensional hybrid MOF is proposed that is co-doped with six equally branched star morphologies. The Co-C composite has the same six-branched morphology as that of the precursor. When the EM wave is incident, this special structure makes it easier for the EM wave to enter the material vertically due to the expansion of the incident surface, which is effective in adjusting the transmission path of the electron and the reflection and distribution of the EM wave. Because of the special morphology and magneto-dielectric synergy, the Co-C composite shows a minimum reflection loss ( R Lmin ) of −48.5 dB at 11.0 GHz at an absorption thickness of 3.0 mm, with a microwave absorption bandwidth (EAB) of 6.1 GHz. This research provides a practical guidance for preparing the MAMs of special star structure.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yuxin Bi,Mingliang Ma,Zijian Liao,Zhouyu Tong,Yan Chen,Rongzhen Wang,Yong Ma,Guanglei Wu
The conductive networks for electron hopping and migration constructed by one-dimensional (1D) composite absorbers are highly desirable to improve the electromagnetic (EM) wave attenuation capacity. Herein, the Ni@Co/C@polypyrrole (PPy) composites integrating the advantages of component and microstructure were fabricated. The addition of Co/C and PPy effectively optimized the impedance matching and improved the EM attenuation. Under the comprehensive impacts of multiple reflections/scattering, conduction loss and interface polarization, the Ni@Co/C@PPy composites showed superior EM wave absorption with the reflection loss (RL) value of −48.76 dB and the effective absorption bandwidth (EAB) of 5.10 GHz at a corresponding thickness of 2.0 mm. The largest EAB could reach 5.54 GHz (7.24–12.78 GHz) at the thickness of 2.2 mm. This work provides a great reference for fabricating 1D novel EM wave absorption materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Shiqi Zhu,Yu Gao,Haoran Zhou,Chunlin Zheng,Xubin Li,Qikui Man,Xincai Liu
The development of microwave absorption materials with good environmental adaptability is a hot topic in the electromagnetic protection field. In this research, Expanded graphite (EG)/ZIF-67 nanocubes-derived (Co@C) composites were successfully fabricated by electrostatic assembly and subsequent heat treatment. The results show that the involvement of an appropriate content of Co@C not only overcomes the problem of single EG impedance mismatch but also introduces additional magnetic loss for the absorber. At the thicknesses of 1.6 mm and 1.5 mm, an effective absorption bandwidth (EAB) of 4.52 GHz and a minimum reflection loss (RL min ) of −48.4 dB were achieved for the Z2-700 sample with a low filling ratio (20 wt%). The enhancement of EMW-absorption performance is attributed to the optimization of impedance matching and the synergistic action between multiple loss mechanisms. Electrochemical corrosion test showed that graphite nanoflakes of EG enhanced the transfer resistance during corrosion, and the corrosion resistance of pure Co@C was enhanced with the protection of EG. This work provides a reasonable attempt to design and fabricate efficient microwave absorption materials suitable for harsh environments.
研究领域:
材料科学
·
电磁学
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Yan Wang,Xiaochuang Di,Xiang Gao,Xinming Wu,Ping Wang
Lightweight and high-efficiency microwave absorbers have received considerable focus in military as well as civil fields. In this work, a unique method was employed to synthesize the Co@C polyhedrons covalently-grafted on magnetic graphene derived from MOF via amino reaction, followed by reduction and high-temperature pyrolysis processes. The results demonstrate that after a series of reaction procedures, Co@C polyhedrons are could be successfully linked to the magnetic NRGO by esterification reaction. The microwave absorption outcomes results indicate that the maximum R L of Co@C@NRGO can achieve up to −73.4 dB at 12.1 GHz with an absorber thickness of 2 mm, and the absorption bandwidth (90% absorption efficiency) is as wide as 5.3 GHz (from 9.9 to 15.2 GHz) with the content of 20 wt%. The microwave absorption mechanisms reveal that the covalent bonds between Co@C and NRGO can accelerate the electron transport and facilitate the formation of a conductive network. Meanwhile, the preferable impedance matching, strong attenuation ability, multiple interfacial polarization, and well good complementarities contribute to promoting the promotion of the EM wave absorption capacity of Co@C@NRGO hybrid. Considering the outstanding performance, the as-prepared Co@C@NRGO composite held by covalent bonding can provide an inspiration for the construction of novel microwave absorbers.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
SYNTHETIC METALS
·
2019
·
IF 2.87
Chen Fu,Dawei He,Yongsheng Wang,Xuan Zhao
In this study, Co nanoparticles coated with N-doped carbon films (Co@C) were fabricated using the facile one-pot method. Further, the microwave absorption performance of Co@C prepared at different calcination temperatures was evaluated. When calcinating at 700 °C, the reflection loss values of Co@C are lower than −20 dB with a thickness of 1.5–5.5 mm. The Co particles show enhanced resonation loss with the in situ growth of Co@C on the graphene oxide surface. The presence of reduced graphene oxide (RGO) can prevent agglomeration and reduce the loading content with excellent microwave absorption performance. As expected, the minimum reflection loss of Co@C/RGO reached −44.14 dB when the loading content was only 15% in a paraffin matrix. The considerable microwave absorption performance of this composite can be attributed to the enhanced impedance matching and large interface contact as well as dipolar polarization induced by RGO. This Co@C/RGO composite exhibiting enhanced microwave ability is considered to be an excellent candidate for developing lightweight microwave-absorbing materials.
研究领域:
材料科学
·
纳米技术
·
电磁材料
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 17
·7639-7645
·
IF 2.7
Qianxi Wang,Yuyu Dai,Xueli Hong,Yunyang Hong,Rui Zhang,Xinhuan Yan
Non-precious metal catalysts play a significant role in the field of hydrogenation. This study synthesized Co-BTC from cobalt nitrate hexahydrate and 1,3,5-tricarboxylic acid benzene. By changing the calcination temperature of Co-BTC in an inert atmosphere, a series of novel non-precious metal Co/C microsphere catalysts were successfully prepared. The composition and structure of the Co/C-n catalysts were characterised by FESEM, TEM, XRD, IR, XPS and BET. These results confirm that 1,3,5-benzenetricarboxylic acid provides a rich carbon matrix and metallic Co nanoparticles are generated by self-reduction on the carbon matrix. The graphite matrix formed during the calcination process has a rich pore structure and good dispersion of active components on the catalyst surface, which is very favourable for the catalytic reaction. In the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN), the Co/C-500 catalyst showed the best catalytic performance. At 80 °C and 2 MPa H2 for 60 minutes, the conversion rate of o-CNB reached 99% and the selectivity reached 99%. When the reaction takes 5 minutes, the conversion rate reaches 10.5%, and the TOF value reaches 36.3 h−1. The Co/C-500 catalyst can be easily recycled and reused after reaction with the help of a magnetic field. Moreover, this catalyst is also effective in the selective hydrogenation of other nitroaromatic hydrocarbons containing halogen or unsaturated groups to corresponding aniline. This simple and direct synthesis method may lead to the economic production of large-scale Co/C catalysts, which is an attractive prospect for the industrial trial production of corresponding aniline.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Yongsong Ma,Kaifa Du,Yifan Guo,Mengyi Tang,Huayi Yin,Xuhui Mao,Dihua Wang
Despite the vital roles of Co nanoparticles catalytic oxidation in the Fenton-like system for eliminating pollutants, contributions of Co phases are typically overlooked. Herein, a biphase Co@C core-shell catalyst was synthesized by the electrochemical co-reduction of CaCO 3 and Co 3 O 4 in molten carbonate. Unlike the traditional pyrolysis method that is performed over 700 °C, the electrolysis was deployed at 450 °C, at which biphase structures, i.e., face-centered cubic (FCC) and hexagonal close-packed (HCP) structures, can be obtained. The biphase Co@C shows excellent catalytic oxidation performance of diethyl phthalate (DEP) with a high turnover frequency value (TOF, 28.14 min –1 ) and low catalyst dosage (4 mg L –1 ). Furthermore, density functional theory (DFT) calculations confirm that the synergistic catalytic effect of biphase Co@C is the enhancement for the breaking of the peroxide O–O bond and the charge transfer from catalysts to PMS molecule for the activation. Moreover, the results of radicals quenching experiments and electron paramagnetic resonance (EPR) tests confirm that SO 4 •– , •OH, O 2 •– , and 1 O 2 co-degrade DEP. Remarkably, 100% removals of three model contaminants, including DEP, sulfamethoxazole (SMX) and 2,4-dichlorophen (2,4-DCP), were achieved, either in pure water or actual river water. This paper provides an electrochemical pathway to leverage the phase of catalysts and thereby mediate their catalytic capability for remediating refractory organic contaminants .
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS LETTERS
·
2019
·Vol. 150
·期 1
·178-184
·
IF 2.372
Li Zhi-Xin,Wei Xian-Yong,Yang Zheng,Zhang Min,Meng Xing-Long,Niu Shuo,Zhang Di,Zong Zhi-Min
Abstract Highly selective hydrogenation of furfural to furan-2-ylmethanol (FM) in isopropanol was achieved over a novel magnetic Cu–Co/C derived from zeolitic imidazolate frameworks prepared by galvanic replacement reaction. Furfural conversion and FM selectivity (FMS) are 100% and 97.2%, respectively, at 200 °C. FMS was held around 95% after 5-times recycle of the Cu–Co/C. In addition, cinnamaldehyde was completely converted with 96.8% of phenylpropanol selectivity over the Cu–Co/C at 150 °C. Graphic Abstract
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2023
·
IF 3.8
Fuping Tian,Xinchi Zhang,Yingying Sheng,Xiao Chen,Xiang Wang,Changhai Liang
The liquid phase selective hydrogenation of cinnamaldehyde has been investigated over the catalysts Co-C- T ( T = 400–700 °C), which were derived from the carbonization of the MOF precursor Co-BTC at different temperatures in inert atmosphere. Co-C-500 exhibited a higher conversion (85.3%) than those carbonized at other temperatures, with 51.5% selectivity to cinnamyl alcohol, under a mild condition (90 °C, 4 h, 2 MPa H 2 , solvent: 9 ml ethanol and 1 ml water). The high catalytic activity of Co-C-500 can be ascribed to the large specific surface area of the catalyst, the uniformly dispersed metallic cobalt nanoparticles , and the more defect sites on the carbon support. Moreover, Co-C-500 showed excellent reusability in 5 successive cycles, mainly related to the uniformly dispersed cobalt nanoparticles embedded in carbon support.
研究领域:
化学工程
·
催化材料
✓ 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）