JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yan Wang,Xiaochuang Di,Zhao Lu,Xinming Wu
Nowadays, electromagnetic (EM) radiation poses severe environmental pollution and harm to civilian and military life. To this end, it is urgent to synthesize high-efficiency microwave absorbers in terms of composition and structural design. Herein, we reported a unique hybrid nanostructure with Co particles embedded in hollow carbon polyhedron by a series of synthetic steps including carbonization and pyrolysis . Further, the nanoporous carbon (NPC) derived from wheat flour is coated onto the surface of Co@C polyhedrons, forming a special hierarchical structure (Co@C@NPC), which demonstrates outstanding microwave absorption properties due to the hierarchical porous structure, enhanced interfacial polarization, conduction loss, multi-reflection and matched impedance. Typically, with a 10 wt% filler content, the maximum R L of Co@C@NPC reaches −57.2 dB at 9.6 GHz and the corresponding effective bandwidth is 5.7 GHz (from 7.5 to 13.2 GHz) with an absorber thickness of 3 mm. Besides, the filler loading of 10 wt% is much lower than other reported bio-derived absorbers. In short, the hybrid zeolitic imidazolate frameworks offer a novel idea for constructing hollow carbon skeletons and introducing biomass carbon as a green, low cost and renewable material that enhances the dielectric loss and the synergistic effect between permittivity and permeability.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2023
·Vol. 17
·期 1
·200
·
IF 3.4
Hong Li,Hongyang Li,Bo Sheng,Bing Zheng,Sujun Shi,Qing Cai,Wenqi Xu,Xiuchen Zhao,Ying Liu
As the integration technology for integrated circuit (IC) packaging continues to advance, the issue of electromagnetic interference in IC packaging becomes increasingly prominent. Magnetic materials, acknowledged for their superior electromagnetic absorption capabilities, play a pivotal role in mitigating electromagnetic interference problems. In this study, we employed a liquid-phase reduction method. We prepared three types of cobalt (Co) particles with distinct morphologies. Through variations in the synthesis process conditions, we were able to control the aspect ratio of protrusions on the surface of the Co particles. It was found that the sword-like Co particles exhibit superior electromagnetic wave absorption capabilities, showing a reflection loss value of up to −50.96 dB. Notably, when the coating thickness is only 1.6 mm, the effective absorption bandwidth is extended up to 7.6 GHz. The spatially expansive sword-like Co particles, with their unique structure featuring dipole polarization and interfacial polarization, demonstrated enhanced dielectric and magnetic loss capabilities, concurrently showcasing superior impedance-matching performance.Keywords:electronics packaging technology;cobalt particles;electromagnetic wave absorber;effective absorption bandwidth
研究领域:
材料科学
·
电磁学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CARBON
·
2023
·
IF 10.9
Shijie Wang,Xue Zhang,Yunxiang Tang,Shuyan Hao,Sinan Zheng,Jing Qiao,Zhou Wang,Lili Wu,Jiurong Liu,Fenglong Wang
Biomass chitosan-derived porous carbon-based materials take the advantage of light weight, adjustable intrinsic conductivity, and environmental friendliness, attracting more attention in the field of electromagnetic compatibility. However, exploring a facile fabrication method to achieve rational structure design and electrical-magnetic coupling for electromagnetic absorption performance enhancement still remains challenging. Here, a unique honeycomb-like porous cobalt/carbon aerogel is fabricated through the directional freezing-drying and carbonization process, and abundant and even-distributed cobalt particles in-situ grow on the carbon skeletons. The aerogel exhibits an impressive electromagnetic wave absorption performance of a −75.8-dB absorption intensity and a −256.9-dB mm −1 specific reflection loss at a low filling content (10%), as well as an 8.53-GHz effective absorption bandwidth. Besides, the aerogel also demonstrates classy radar stealth and thermal insulation performance. The eco-friendly, easily fabricated, and high-performance cobalt/carbon aerogel suggests broad application prospects for electromagnetic compatibility and protection, thermal management, and multifarious electron devices.
研究领域:
材料科学
·
环境科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Green Energy & Environment
·
2020
·
IF 6.395
Qiongguang Li,Yanhong Wang,Jing Yu,Menglei Yuan,Qiangqiang Tan,Ziyi Zhong,Fabing Su
To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles, we synthesized a superstructure of Si@Co–NC composite via the carbonization of zeolite imidazolate frameworks incorporated with Si nanoparticles. The Si@Co–NC is comprised of Si-nanoparticle core and N-doped/Co-incorporated carbon shell, and there is void space between the core and the shell. When using as anode material for LIBs , Si@Co–NC displayed a super performance with a charge/discharge capacity of 191.6/191.4 mA h g −1 and a coulombic efficiency of 100.1% at 1000 mA g −1 after 3000 cycles, and the capacity loss rate is 0.022% per cycle only. The excellent electrochemical property of Si@Co–NC is because its electronic conductivity is enhanced by doping the carbon shell with N atoms and by incorporating with Co particles, and the pathway of lithium ions transmission is shortened by the hollow structure and abundant mesopores in the carbon shell. Also, the volume expansion of Si nanoparticles is well accommodated in the void space and suppressed by the carbon host matrix. This work shows that, through designing a superstructure for the anode materials, we can synergistically reduce the work function and introduce the confinement effect , thus significantly enhancing the anode materials' electrochemical performance in LIBs.
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
JOURNAL OF CATALYSIS
·
2016
·
IF 7.354
Liang Wei,Yanxi Zhao,Yuhua Zhang,Chengchao Liu,Jingping Hong,Haifeng Xiong,Jinlin Li
Three-dimensional mesoporous cellular silica foams (MCFs) were prepared and used as supports for cobalt Fischer–Tropsch synthesis (FTS) catalysts (Co/MCF). The silica foam MCFs have a 3D mesostructure with large spherical cell pores interconnected with small window pores, which provides an open porous network for Co FTS catalysts. The effects of catalyst structure parameters (cell pore diameter and cobalt particle size) on the performance of the Co/MCF catalysts were investigated. It was found that the Co/MCF catalyst with average pore size 7–12 nm (window and cell pores) showed the highest reactivity. The MCF not only provided a cavity to suppress the growth of cobalt particles, but also enhanced the reducibility and cobalt dispersion. The Co/MCF catalysts having a large and open pore structure are favorable for the transport of reactants and the occurrence of secondary reactions, leading to high C 5+ hydrocarbon selectivity. A Co/MCF catalyst with Co particle size 6.9 nm presented the highest activity in the FTS reaction due to its having the highest dispersion and an appropriate degree of reduction. Compared with the Co catalysts supported on other ordered silicas (SBA-16, KIT-6, and SBA-15), the Co/MCF catalyst showed higher activity and C 5+ hydrocarbon selectivity, which was attributed to the 3D open porous structure of MCF. The Co/MCF catalysts are stable under low-temperature FTS conditions (210 °C). Under harsh FTS reaction conditions (250 °C, 1.0 MPa), the Co/MCF catalyst underwent rapid deactivation due to cobalt sintering and the formation of interacting Co–silica compound, while the stability of the Co/MCF catalyst can be improved by functionalizing the MCF using carbon coating and Al doping.
研究领域:
化学工程
·
材料科学
·
催化
✓ 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）