NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 40
·19161-19167
·
IF 3.925
Peng Miao,Weixing Chen,Kailei Li,Weifeng Zhao,Jie Kong
Design of microwave absorbents with hierarchical interfacial structures has become an effective method to scatter microwaves. Metal/carbon composites derived from metal–organic frameworks (MOFs) have attracted considerable attention due to their tunable chemical composition and microstructure. We describe the facile synthesis of a Co/CoO/FeO/C nanocomplex employing Co(OH)2 on NH2-MIL-88B as the “sacrificial template” through one-step pyrolysis. The as-prepared flaky-like Co/CoO/FeO/C nanocomplex showed an effective absorption width of 4.7 GHz at 1.86 mm and a minimum reflection loss of −45.5 dB at 2.01 mm. Our study can aid design of a microstructural strategy for preparing high-performance microwave absorbents.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuan Shu,Tingkai Zhao,Jalil abdul,Xianghong Li,Lei Yang,Fa Luo
Addressing the growing issue of electromagnetic radiation calls for urgent exploration of effective electromagnetic wave absorbers. Herein, a series of coral-like Co/CoO nanoparticles/reduced graphene oxide (Co/CoO/RGO) hybrid aerogels were synthesized via a freeze drying-thermal reduction strategy. Their advantages involving porous interconnected framework, abundant heterogeneous interfaces, and integration of dielectric/magnetic units could bring multiple loss modes. By manipulating the Co(CO 3 ) 0.5 (OH)·0.11H 2 O (CCOH) addition and reduction temperature, the electromagnetic parameters could be tuned, ultimately resulting in optimal absorption capability with maximal reflection loss of –32.4 dB and effective bandwidth of 4.2 GHz. More importantly, excepting the high electromagnetic wave loss, Co/CoO/RGO hybrid aerogels also exhibit good hydrophobicity and thermal insulation properties, making them suitable for application in harsh environment. Besides, the special structure and multiple components lead to multiple heterointerfaces in aerogels, the resultant interface polarization is deemed to contribute to electromagnetic wave loss. Here, Density Functional Theory (DFT) simulation based on first-principles is adopted to verify the contribution of interface polarization from the theoretical level. According to the simulation results, the electron-occupied states near the Fermi level are significantly different among the different phases comprising the heterointerfaces, and there is a noticeable accumulation of charge at these interfaces, successfully affirming the interface polarization behavior at different interfaces.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
CARBON
·
2023
·
IF 10.9
Yuan Shu,Tingkai Zhao,Xianghong Li,abdul Jalil,Lei Yang,Guyue Feng,Yatao Li,Weiyu Jia,Fa Luo
To optimize the electromagnetic wave performance for absorbers, it is crucial to implement rational structural designs and integrate multiple loss modes in a coordinated manner. Here, three-dimensional (3D) porous macroscopic coral-like Co/CoO/reduced graphene oxide aerogels (Co/CoO/RGO), are successfully fabricated by an ice-templated freeze-drying and thermal reduction techniques, and their pore structures , involving aperture and total pore volume , are availably regulated by manipulating the water addition. The electromagnetic parameters and electromagnetic wave performance appear strong response toward the variation of pore structure. By controlling the pore structure, these parameters can be efficaciously tunned, thus manipulating the performance. The optimized absorption performance is obtained when the water addition is 1 ml, the minimum reflection loss reaches to −61.8 dB and the effective bandwidth is 4.2 GHz. Such good performance is inseparable with the 3D crosslinked conductive framework, the hybrid of magnetic and dielectric units, numerous heterointerfaces and countless pores walls in aerogels, which brings multiple electromagnetic wave loss mechanism. Moreover, it is very important that Co/CoO/RGO aerogels also integrate good hydrophobicity and heat insulation properties, allowing their application in harsh conditions. This work shows the potential of pore structural control engineering for producing multifunctional aerogels.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Xuedong Wei,Na Li,Xianming Zhang
Two kinds of three-phase composite materials, Co/Co(OH) 2 /C@B directly from ZIF67 modified by NaBH 4 and Co/CoO/C@B through pyrolyzation of Co/Co(OH) 2 /C@B material, are successfully synthesized and used as catalysts for the oxygen evolution reaction (OER). The structure and morphology are mainly characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS). HBZ-1 sample with the structure of Co/Co(OH) 2 /C@B has the best onset potential of 1.075 V vs. RHE at 0.1 mA cm −2 and the best catalyst stability among all of the materials researched. Especially as its pyrolyzing product, the CBZ-1 sample with the structure of Co/CoO/C@B behaves the most excellent synthetically electrocatalytic performance with low onset potential of 1.444 V vs. RHE at 0.1 mA cm −2 and a small overpotential of 390 mV at 10 mA cm −2 , which is better than that of RuO 2 . This good catalytic activity is mainly attributed to the generation of CoO phase and synergistic effect of all the phases in the composite structure. Furthermore, the CBZ-1 sample has the appropriate catalytic stability which attributed to the three-phase structure of Co/CoO/C@B composite and the existing of a little B element.
研究领域:
材料科学
·
电催化
·
纳米材料
·
能量转换
·
无机化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yingjie Chen,Chong Gong,Zhihao Shi,Di Chen,Xing Chen,Qian Zhang,Beili Pang,Jianguang Feng,Liyan Yu,Lifeng Dong
A melt-salt-assisted method is utilized to construct an onion-like hybrid with Co/CoO nanoparticles embedded in graphitic Fe-N-doped carbon shells (Co/CoO@FeNC) as a bifunctional electrocatalyst. The iron-polypyrrole (Fe-PPy) is firstly prepared with a reverse emulsion. Direct pyrolysis of Fe-PPy yields turbostratic Fe-N-doped carbon (FeNC) with excellent oxygen reduction reaction (ORR) electrocatalysis, while the melt salt (CoCl 2 ) mediated pyrolysis of Fe-PPy obtains onion-like Co/CoO@FeNC with a reversible overvoltage value of 0.695 V, largely superior to Pt/C and IrO 2 (0.771 V) and other Co-based catalysts reported so far. The ORR activity is mainly due to the graphitic FeNC and further enhanced by Co N x bonds, whereas the oxygen evolution reaction (OER) activity is principally due to the Co/CoO composite. Concurrently, Co/CoO@FeNC as cathode catalyst enables Zn-air battery with a high open circuit voltage of 1.42 V, a peak power density of 132.8 mW cm −2 , a specific capacity of 813 mAh g Zn −1 , and long-term stability.
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
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Keke Yang,Guilin Song,Yuanyuan Li,Qingda An,Shangru Zhai,Zuoyi Xiao
Nowadays there is much room for improvement in the designed synthesis of high-performance electromagnetic wave absorbers by combining metal-organic frameworks (MOFs) and biomass components. Herein, 3D N-doped porous carbon cobalt/cobalt oxide (NPC/Co/CoO) composites were successfully prepared by transforming in-situ grown ZIF-67 clusters on a chitosan matrix. Analysis results showed that the N-doped carbonaceous composites obtained had unique porosity, high specific surface area, and defect-enriched structure, which provided numerous paths for electron transfer , leading to big benefits to interfacial polarization and dipole polarization. Most importantly, the ferromagnetic resonance and magnetic coupling were enhanced by ZIF-67-derived Co/CoO nanoparticles . By adjusting the content of metallic cobalt salt, pyrolysis temperature, and sample filling content, the optimal impedance matching properties of the composites could be optimized. When the matching thickness is 2 mm, the RL min of NPC/Co/CoO-10/700–30 wt% achieved − 48.97 dB at 13.52 GHz, and the effective absorption bandwidth exceeds 5.36 GHz. The composites with excellent performance prepared by a controllable process using chitosan and ZIF-67 might be a promising alternative for the large-scale preparation of high-frequency electromagnetic wave absorbers.
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
Nanoscale
·
2016
·Vol. 8
·期 8
·4681-4687
·
IF 7.76
Zexing Wu,Jie Wang,Lili Han,Ruoqian Lin,Hongfang Liu,Huolin L. Xin,Deli Wang
Investigating active, stable, and low-cost materials for the oxygen reduction reaction is one of the key challenges in fuel-cell research. In this work, we describe the formation of N-doped carbon shell coated Co@CoO nanoparticles supported on Vulcan XC-72 carbon materials (Co@CoO@N–C/C) based on a simple supramolecular gel-assisted method. The double-shelled Co@CoO@N–C/C core–shell nanoparticles exhibit superior electrocatalytic activities for the oxygen reduction reaction compared to N-doped carbon and cobalt oxides, demonstrating the synergistic effect of the hybrid nanomaterials. Notably, the Co@CoO@N–C/C nanoparticles give rise to a comparable four-electron selectivity, long-term stability, and high methanol tolerance; all show a multi-fold improvement over the commercial Pt/C catalyst. The progress is of great importance in exploring advanced non-precious metal-based electrocatalysts for fuel cell applications.
研究领域:
材料科学
·
电化学
·
能源研究
✓ 已验证
DOI
高影响因子
Materials
·
2024
·Vol. 17
·期 21
·5239
·
IF 3.1
He Han,Hui Chen,Rui Wang,Zhichao Lou
With the popularization of wireless communication, radar, and electronic devices, the hidden harm of electromagnetic radiation is becoming increasingly serious. The design of green biomass carbon-based interface heterojunctions based on lightweight porous materials can effectively protect against electromagnetic radiation hazards. In this work, we constructed an anisotropic heterojunction interface with magnetic and dielectric coupling based on a honeycomb-like periodic matrix multi-layer array repeating unit. The removal of lignin components from bamboo through oxidation enriches the impregnation pores and uniform adsorption sites of the magnetic medium. Further, in situ pyrolysis promotes the formation of a large number of electric dipoles at the interface between the magnetic medium and dielectric coupling inside the periodic cell carbon skeleton, enhancing interface polarization and relaxation. Local carrier traps and uneven electromagnetic density enhance dielectric and hysteresis losses, resulting in excellent impedance matching. Therefore, the obtained bamboo-based carbon multiphase composite absorbent has satisfactory electromagnetic loss characteristics. At a thickness of 1.55 mm, the effective absorption bandwidth reaches 5.1 GHz, and the minimum reflection loss (RL) value reaches −54.7 dB. In addition, the far-field radar simulation results show that the sample has an excellent RCS (radar cross-section) reduction of 33.3 dB·m2. This work provides new directions for the diversified development of green biomass and the optimization of the design of magnetic and dielectric coupling in periodic array structures.
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
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yongqian Shen,Guibin Zhang,Haiyan Wang,Xin Liu,Yuchen Zhang,Feng Gao,Fulong Yang,Jiqiang Ma,Jiafeng Cao,Huixia Feng,Xueyan Du
In recent years, magnetic metal nanoparticles (NPs)/carbon nanofibers (CNFs) composites have become very promising electromagnetic waves (EMWs) absorbers. However, how to achieve controllable growth of magnetic metals in CNFs is still an urgent problem to be solved. Herein, we reported a pore-confined strategy for constructing the porous Co/CoO/CNFs. By introducing different amounts of acetone (0.20 g, 0.30 g and 0.40 g) into the aqueous phase spinning solution to construct the porous structure , we achieved uniform distribution of Co/CoO NPs and ultimately obtained the porous Co/CoO/CNFs microwave absorbers (MAs) with excellent microwave absorption performance. Thanks to the excellent impedance matching and enhanced polarization loss, the porous Co/CoO/CNFs obtained the minimum reflection loss (RL) of −52.2 dB with a thickness of 3.0 mm, and the effective bandwidth (EBW) was 3.02 GHz when the acetone addition in the spinning solution was 0.30 g. Therefore, the pore-confined strategy proposed herein is conducive to the design of the MAs with excellent performance and low infilling rates based on CNFs. Furthermore, the porous structure of CNFs also improves the lightweight performance of the MAs.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
ChemSusChem
·
2024
·
IF 7.5
Xin Tian,Mengnan Xu,Xin Ma,Guanyu Mu,Junwu Xiao,Shuai Wang
Graphical The 3D Co-based/graphene composite framework, prepared by spontaneous assembly, serves as the template and sources of Co and O.The as-formed Co-Nx sites, along with the Co/CoO nanoparticles and N-doped carbon nanosheets, synergistically function as the active sites to boost the electrocatalytic activity of the oxygen redox reaction. The Co/CoO-NG exhibits a low potential gap (ΔE=0.784 V) for ORR/OER. Reasonable design of low-cost, high-efficiency and stable bifunctional oxygen electrocatalysts is of great significance to improve the reaction efficiency of Zn-air batteries, which is still a huge challenge. Here, we report a highly efficient bifunctional oxygen electrocatalyst with three-dimensional (3D) N-doped graphene network-supported cobalt and cobalt oxide nanoparticles (Co/CoO-NG), which can be in situ synthesized by inducing metal ions on metal plates via graphene oxide as an inducer. This 3D network structure and open active center show excellent bifunctional oxygen electrocatalytic activity under alkaline conditions, and can be used as an air electrode in rechargeable Zn-air batteries, with significantly better power density (244.28 mW cm −2 ) and stability (over 340 h) than commercial Pt/C+RuO 2 mixtures. This work is conducive to advancing the practical application of graphene-based materials as air electrodes for rechargeable zinc-air batteries.
研究领域:
材料科学
·
电化学
·
能源存储与转换
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Yuanhui Zuo,Mujia Huang,Wenchao Sheng,Qian Xu,Wenquan Tao,Zhuo Li
To develop high-performance non-precious metal-based electrocatalysts for oxygen reduction reaction (ORR) is an urgent demand. We herein report an ingenious strategy to develop highly selective and competitive precious metal-free ORR electrocatalyst Co/CoO/SnO encapsulated in N-rich mesoporous carbon (CCS@NPC) nanocubes, via a simple one-step introduction of all functional components. Atomically mixed composites with significantly enhanced catalytic activity were obtained by adopting amorphous mesoporous ternary metal oxides CoSnO 3 nanocubes as precursor and template. The synergistic effect of the triphase nanohybrids (Co, CoO & SnO) anchored in nitrogen-doped mesoporous carbon nanocubes promoted the catalytic reactions , owning to the anisotropic morphology, great heterojunction interfaces, and structural stability. The large-scale prepared CCS@NPC exhibited excellent electrocatalytic activity toward ORR with an admirable onset potential (1.01 V) and diffusion-limited current density (5.88 mA cm −2 ). The CCS@NPC showed stronger stability (20 h) and higher methanol tolerance with the concentration up to 8.0 M, compared to that of commercial Pt/C.
研究领域:
材料科学
·
电化学
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2026
·Vol. 42
·期 31
·22973-22982
·
IF 4.4
Jia Xiaomeng,Dong Kaiyu,Zheng Zhe,Sheng Tian,Yuan Qiang
Nonprecious metal oxygen reduction
reaction (ORR) electrocatalysts
have garnered increasing attention owing to their extremely low cost
compared with Pt-based electrocatalysts. However, realizing the four-electron
pathway and developing highly antipoisoning nonprecious metal ORR
electrocatalysts are key challenges in practical energy devices. Herein,
atomic-level Fe doping was applied to Co@CoO core–shell nanoparticles
anchored in a porous carbon–nitrogen framework (denoted Fe–Co@CoO/NC)
derived from FeCoZn metal–organic frameworks. The Fe–Co@CoO/NC
exhibits a half-wave potential of 0.895 V in an alkaline medium, superior
to that of commercial Pt/C (0.842 V), and high in situ methanol and
CO tolerance. In situ spectroscopic characterizations and Rotating
Ring-Disc Electrode (RRDE) investigations reveal that four-electron
ORR is achieved using Fe–Co@CoO/NC through O–O bond
breaking in OOH* intermediate species. In addition, density functional
theory calculations show that compared with Pt, Fe–CoO effectively
suppresses H 2 O 2 generation and favors a more
advantageous four-electron reaction pathway. Fe–Co@CoO/NC as
a cathode material for direct methanol fuel cells (DMFCs) reaches
a peak power density of 113.7 mW·cm –2 , markedly
outperforming commercial Pt/C (72.0 mW·cm –2 ). This work provides an effective strategy for preparing high-efficiency
nonprecious metal four-electron ORR catalysts with intrinsic tolerance
to methanol and CO for DMFC devices.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）