INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Qiao Wu,Tianle Li,Wenju Wang,Yupeng Xiao
Oxygen evolution reaction (OER) is a key part of water electrolysis for hydrogen production . Non-noble-metal catalysts with high activity, stability, but low cost are prerequisites for practical application. In this work, sucrose char was synthesized and then chainmail catalysts were produced by in situ growth method, defined as M@C (M = Fe, Co and FeCo). FeCo@C showed great OER performance in both catalytic activity and durability tests. The overpotentials were 302 mV (at the current density of 10 mA cm −2 ) and 423 mV (at 50 mA cm −2 ), with a lowest Tafel slope of 75 mV dec −1 . The electrochemical surface area of catalysts were also analyzed by calculating the capacitance of the double layer to further investigate the catalytic activity. Furthermore, FeCo@C showed superior stability after 30 h test or 10,000 cycles of cyclic voltammetry . Theoretical calculation based on density functional theory (DFT) demonstrated that the overpotential of OER was determined by the Gibbs free energies of reaction intermediates HO∗, O∗ and HOO∗. The adsorption of HO∗ radicals onto the FeCo@C was weaker than Fe@C, which was favorable for reducing the overpotential, as the rate-determining step of the OER process over these catalysts was that HO∗ dehydrogenated to form O∗.
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
·
2022
·
IF 6.371
Hua Ma,Xiuwen Wu,Xiuli Fu,Zhijian Peng
The development of a facile strategy to fabricate inexpensive and efficient nonnoble metal-based alloys to replace their traditionally costly noble-metal counterparts for electrocatalytic water splitting holds great appeal. Here, we report novel FeNi-FeCo-C composite nanofibers (FeNi-FeCo-C CNFs), which was prepared simply by electrospinning a precursor solution containing Fe, Ni and Co nitrates together with polyacrylonitrile powders and subsequent thermal treatment. The optimal FeNi-FeCo-C CNFs prepared with 10 wt% polyacrylonitrile at a thermal treatment temperature of 800 °C show excellent electrocatalytic performance for oxygen evolution in a 1 mol·L −1 KOH aqueous solution with a relatively small overpotential of 262 mV at 10 mA cm −2 , a low Tafel slope of 47.2 mV dec −1 , and excellent cycling stability. The present strategy will provide new insight for the design and fabrication of electrocatalysts for water splitting.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 36
·18863-18871
·
IF 11.301
Ye Xiong,Lulu Xu,Caixia Yang,Qingfeng Sun,Xijin Xu
Adjusting the electromagnetic parameters by decorating magnetic particles for improved impedance matching is an important strategy for obtaining lightweight and efficient carbon-based electromagnetic wave-absorbing materials. In this work, a tomato-like hierarchical porous FeCo/C@WC was prepared for efficient microwave absorption, in which a lightweight anisotropic wood carbon aerogel (WC) was used as a structural assistant, and a MOF-derived graphitized carbon-coated FeCo alloy (FeCo/C) served as a dielectric/magnetic regulator. The tomato-like polystage micro-nano construction was made up of a “pericarp” left by the parallel channels of natural wood, a “pulp tissue” of the MOF-derived nanocage and “seeds” of FeCo nanoalloys embedded in a nanocage. The macroporous wooden shell and mesoporous carbon nanocage gave the composite an excellent hierarchical dielectric coupling network. Meanwhile, the uniformly dispersed FeCo nanoparticles enhanced the magnetic loss to the carbonaceous substrate, allowing for better impedance matching. As a result, the constructed multidimensional FeCo/C@WC exhibited superior wave absorbing ability, in which the maximum reflection loss (RL) reached −47.6 dB and the wide absorption bandwidth was up to 8.9 GHz. These excellent results confirmed that wood-based electromagnetic absorption devices may have a good application prospect.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
Advanced Composites and Hybrid Materials
·
2024
·Vol. 7
·期 6
·1-14
·
IF 23.2
Qiu Jiahang,Zhang Mu,Zhao Rongzhi,Sun Xudong,He Dianning
The quest for broadband electromagnetic wave absorption to satisfy the demands of various fields has emerged as a prominent research focus in the domain of electromagnetic wave absorption. By considering the effects of magnetic loss and polarization loss across different frequency bands, the development of composite materials incorporating magnetic metal particles and single metal atoms may facilitate an expansion of the electromagnetic wave absorption frequency range. Consequently, we synthesized FeCo@C/Ni@C composites derived from FeCo Prussian blue analogues and polydopamine through wet chemistry and pyrolysis methods. The chelation mechanism of polydopamine, combined with the physical barrier effect provided by Zn ions during synthesis, endows the FeCo@C/Ni@C composite with low-frequency magnetic loss characteristics from the FeCo alloy, high-frequency dipole polarization losses attributed to Ni atoms, and conductivity losses arising from the coupled carbon matrix. Ultimately, the composite exhibits exceptional electromagnetic wave absorption performance: at a thickness of 2.26 mm, it achieves a minimum reflection loss value of − 50.1 dB along with an effective absorption bandwidth reaching up to 6.0 GHz. In summary, this work presents a novel strategy for enhancing broadband absorption capabilities in electromagnetic wave absorbing materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 77
·73020-73027
·
IF 3.289
D. Li,Y. Feng,D. S. Pan,L. W. Jiang,Z. M. Dai,S. J. Li,Y. Wang,J. He,W. Liu,Z. D. Zhang
Cactus-shaped core double-shelled FeCo/C/Fe2.5Cr0.5Se4 nanostructures with a spiky surface were prepared by combining an arc-discharge process with a high-temperature solution chemical method, in which FeCo nanoparticles serve as the, while carbon and ferrimagnetic Fe2.5Cr0.5Se4 (FCS) are the inside and the outside shells, respectively. The magnetic properties, electromagnetic response, and microwave absorption properties of the (x)FeCo/C/FCS nanocomposites in the 1–18 GHz frequency range were investigated by changing the mass ratio x between FeCo/C and FCS. The frequency dependences of μ′′ (imaginary parts of complex permeability) and ε′′ (imaginary parts of complex permittivity) of the (0 ≤ x ≤ 0.15)FeCo/C/FCS nanocomposites show distinct inverse trends of change in the high frequency ranges. Negative minimum values of μ′′ are found to be coupled with positive maxima of ε′′ due to a phase lag. The bare FCS–paraffin composite starts with a minimum μ′′ of about −0.07, which shifts to −0.44 and −0.05 when the mass ratio x is increased to 0.1 and 0.15, respectively. As x increases to 0.2, all the μ′′ values of the nanocomposites become positive. The best absorption property with a reflection loss (RL) peak of −54.5 dB at 10 GHz is obtained in the (x = 0.1)FeCo/C/FCS–paraffin composite and RL exceeding −20 dB can be achieved within the 3–18 GHz frequency range by choosing an appropriate layer thickness between 1.4 and 6 mm. The contribution of the negative μ′′ response to the microwave absorption is discussed.
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 ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Ruiyang Tan,Jintang Zhou,Zhengjun Yao,Bo Wei,Jiaqi Zu,Haiyan Lin,Zhong Li
Magnetic-dielectric composites are widely used in microwave absorption applications and have been continuously concerned by researchers. The synthesis of high-performance microwave absorbers with specific structures is a hot research topic. However, the question on how to reasonably combine the magnetic and dielectric components for achieving excellent microwave absorption performance still remains unanswered. In this study, FeCo/C microspheres were synthesized by a two-step hydrothermal method . FeCo nanoparticles were embedded in carbon spheres and formed the graphite layers, which is similar to Ferrero Rocher® chocolates. The electromagnetic parameters can be effectively adjusted by controlling the hydrothermal reaction time and excellent microwave absorption properties can be achieved at a low filling ratio. The FeCo/C microspheres exhibit the maximum reflection loss of – 20.61 dB and – 51.36 dB at the thickness of 1.6 mm and 2.6 mm, respectively. The effective absorption bandwidth of these microspheres is about 4.3 GHz. The specific Ferrero Rocher® chocolates-like multi-level structure increases to a large extent the material’s conduction loss and polarization relaxation loss. At the same time, the reasonable ratio of the magnetic and dielectric components significantly improves the impedance matching. Therefore, this study is aimed at providing insights into understanding of the absorption mechanism and reliable references to the design of magnetic-dielectric composed microwave absorbers.
研究领域:
材料科学
·
电磁学
·
微波工程
·
纳米技术
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Ling Ding,Ying Huang,Xudong Liu,Zhipeng Xu,Suping Li,Jing Yan,Panbo Liu
The core-shell composite of FeCo alloy coated with amorphous carbon and mesoporous silica (mSiO 2 for short) has been successfully fabricated through liquid-phase reduction, hydrothermal reaction as well as high temperature calcination , forming nanoparticles around 400 nm in size. The alloy core provides strong magnetic loss and keeps stable under the protection of the shell, while the carbon shell reduces density and promotes dielectric loss. The outer layer of mSiO 2 provides a larger specific surface area for multiple reflections, and meanwhile effectively adjusting the impedance matching, resulting in a better absorption. With a thickness of 3.5 mm, the maximum R L of the composite reaches −46.79 dB at 11.84 GHz, and the effective absorption bandwidth with the R L below −10 dB is up to 8.8 GHz (from 9.2 to 18.0 GHz). Hence, FeCo@C@mSiO 2 composite is potential to become an excellent candidate in the field of microwave absorption.
研究领域:
材料科学
·
纳米技术
·
电磁工程
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED POWDER TECHNOLOGY
·
2022
·
IF 4.969
Ximing Zhang,Guiyang Xian,Jingyu Wang,Yang Fan,Yin Liu,Won-chun Oh,Zhenying Liu,Yueqin Wang,Ling Bing Kong
FeCo@C with a hollow porous dodecahedron structure was obtained through carbonization of ZIF-67 etched with Fe 3+ . During the pyrolysis process, the organic skeleton of the ZIF-67 was carbonized, forming graphitic carbon and carbon nanotubes. The etching effect of Fe 3+ with different concentrations on the morphology of ZIF-67 is studied. The MOF-derived porous carbon bimetallic nanocomposites exhibited stronger electromagnetic wave absorption performance than the monometallic ones. Specifically, the optimized sample has a reflection loss of −70.69 dB at 11.28 GHz, as the thickness is 2.07 mm. The enhanced electromagnetic wave (EMW) absorption performance of the nanocomposites can be attributed to the multiple interfaces and capacitive structure formed by catalytically produced carbon nanotubes. This achievement could be used as a reference for the development of MOF-derived porous carbon nanocomposite EMW absorbers.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Yin Wang,Huanhuan Li,Jin Xu,Jiayu Yu,Jinfeng Wang,Hu Jiang,Chengyun Li,Xiaodong Zhang,Ning Liu
Herein, FeCo@C-LFC x (FeCo@C-xLaFeCoO 3 ) materials were prepared by high-temperature carbonation based on the construction of Fe/Co metal–organic framework columns with LaCoO 3 (FeCo-MOF-LFC x ) by in-situ extraction and synchronous coordination growth strategy. This strategy could improve the defects of perovskite materials such as easy aggregation, poor stability and poor specific surface area. The results demonstrated that the degradation rate of FeCo@C-LFC 1.0 for norfloxacin (NOR, 20 mg/L) was 93.81% within 15 min. Co-BTC column nanocolumns and spongy Fe-BTC were successfully formed. Compared with LaFeCoO 3 , the specific surface area (89.9 m 2 /g) and pore volume (0.101 cm 3 /g) of FeCo@C-LFC 1.0 after carbonization were increased by 16.3 times and 9.2 times, respectively. FeCo@C-LFC x could produce more structural defects and coordination unsaturated sites, promote microwave absorption. Vo and C = O on the material surface were involved in the activation of PMS. Moreover, quenching experiments and EPR verified that 1 O 2 , OH, and SO 4 − were the main reactive radicals in the degradation process. The FeCo@C-LFC 1.0 showed excellent reusability and stability. After five experiments, the removal rate of NOR remained at 91.15%. The toxicity of intermediate products was reduced. This work provided new avenues for using FeCo@C-LFC 1.0 for environmental remediation.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2025
·
IF 5.5
Yongjin Tang,Jin Huang,Wei Xiao,Yang Li,Shuoqing Yan,Jun He
Layered MXene-based magnetoelectric composites have been extensively investigated and applied as microwave absorbing (MA) materials. Although multicomponent composite strategies have been proven to significantly improve the MA performance of materials, the fine structural design and optimization of the functional synergy of absorbers at intricate environments remain scientific issues worthy of further exploration. In this study, FeCo@C/Ti3C2Tx MXene composites were synthesized through a combination of chemical vapor deposition and electrostatic self-assembly techniques. The core–shell structure of ultrafine FeCo@C nanoparticles, with an average diameter of 13.51 nm, has effectively mitigated the adverse effects of harsh environmental conditions due to chemical stability of the carbon layer. Furthermore, the integration of ultrafine FeCo@C nanoparticles with a low filler loading contributed to the overall lightweight characteristic. Notably, the FeCo@C/Ti3C2Tx MXene composites with a 20 wt % filling ratio exhibit a minimum reflection loss (RLmin) of −31.6 dB at 1.7 mm and an effective absorption bandwidth of 5.76 GHz at 2.4 mm. The corresponding absorbing coating achieves a maximum reduction in the radar cross-section of 18.86 dBm2. The FeCo@C/Ti3C2Tx MXene composites exhibit the potential for applications in challenging environments, including high-temperature and humid conditions.
研究领域:
材料科学
·
纳米复合材料
·
电磁功能材料
·
微波吸收
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Du Jiawei,Liwen Zhang,Peng Tang,Xueying Zhao,Bo Wang,Guohua Wu,Xuyang Zhang,Nana Liu
The magnetic component is crucial for achieving a high absorption bandwidth within the microwave absorbing materials, while a high loading rate of magnetic particles often leads to agglomeration, which can degrade the absorption performance. The utilization of short-chain ligands generally enhances the constrained growth effect of carbon materials on magnetic particles in metal-organic framework (MOF) derived materials. In this study, a CoFe/C nanorod derived from a MOF composed of nitrilotriacetic acid and cobalt-iron metal ions has been successfully prepared. The MOF-derived method with constrained growth is employed to suppress the aggregation of alloy microparticles and maintaining a high magnetic particles. The optimized composite exhibits an effective absorption bandwidth (EAB) of 7.88 GHz that could cover the Ku-band. The excellent dispersion structure and high loading rates endowed by CoFe/C nanorods with constrained strategy, would contributed to the enhanced wideband microwave absorbing properties. These findings might provide new guidance for the fabrication of noval broadband microwave absorbing materials with high loading of magnetic nanoparticles.
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2021
·Vol. 10
·期 3
·1547-1559
·
IF 12.732
Ran Liu,Gaiping Du,Bin Liao,Weixin Xiao,Zhenguo An,Jingjie Zhang
Due to their multiple dissipation mechanisms, low density and easily tailored impedance matching, heterogeneous hollow structures are promising candidates for microwave absorbents towards wideband absorption and lightweight design. In this work, a new type of hollow microspheres with a porous carbon shell embedded with crystalline FeCo alloy nanoparticles have been prepared via a stepwise spray drying–calcination strategy. The effects of both the FeCo/C molar ratio and the calcination temperature on the structure and property of the porous hollow microspheres (PHMs) have been studied. It is found that the effective absorption bandwidth of the as-prepared FeCo/C PHMs surpassed 7.44 GHz at a matching thickness of 2.64 mm, which covers the full Ku-band. Moreover, with an elevated calcination temperature, high microwave absorbing performance can be achieved at a much reduced matching thickness. A probable absorbing mechanism has been proposed involving the synergistic effect of the hollow interior, the porous shell structure, and the electric and magnetic dissipation due to the coexistence of carbon and magnetic metals. This work opens a new pathway to synthesize microwave absorbents with a heterogeneous hollow structure, and may shed some light on the design and controlled preparation of other hollow structures with various shell compositions.
研究领域:
材料科学
·
电磁学
✓ 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）