Carbon aerogels towards new candidates for double negative metamaterials of low density

Xie, Peitao; Sun, Wei; Liu, Yao; Du, Ai; Zhang, Zidong; Wu, Guangming; Fan, Runhua

doi:10.1016/j.carbon.2017.12.009

Cited by 110 publications

(49 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The calculation results using (7) are shown as red solid lines in Figures 5(a) and S9, and the used parameters are in Table S7. The calculation results agree well with experimental data ( 2 ≈ 0.9975), indicating that the mechanism of negative susceptibility/permeability can be well explained [16]. The physical meaning of a is the initial permeability, and its value should be 1 for Ag/SiO 2 composites, in good agreement with the calculation results (in Table S7).…”

Section: Researchsupporting

confidence: 85%

“…Ac conductivity is also the function of frequency, usually explained by skin depth = (2/ 0 ) 0.5 [18]. The relationship between , j, and can be modified [16]:…”

Section: Researchmentioning

confidence: 99%

“…Peng et al observed the negative electromagnetic parameters in amorphous-metal sensors and transducers, a great success of multifunctionalization of the devices [12,13]. Specifically, Fan et al investigated negative permittivity and/or negative permeability in random percolative composites where conductive functional fillers were randomly distributed in the insulating matrix [14][15][16]. In these so-called intrinsic/random metamaterials, the sizes of the metamaterials are no longer dependent on wavelength, because the negative electromagnetic parameter directly originates from the intrinsic property of component materials.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

et al. 2019

Self Cite

View full text Add to dashboard Cite

Creative Commons Attribution License (CC BY 4.0).The mechanism of negative permittivity/permeability is still unclear in the random metamaterials, where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic. Here silver was introduced into porous SiO 2 microsphere matrix by a self-assemble and template method to construct the random metamaterials. The distribution of silver was restricted among the interstices of SiO 2 microspheres, which lead to the precise regulation of electrical percolation (from hoping to Drude-type conductivity) with increasing silver content. Negative permittivity came from the plasma-like behavior of silver network, and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response. During this process, the frequency of epsilon-near-zero (ENZ) could be adjusted accordingly. Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork. The calculation results indicated that negative permeability has a linear relation with 0.5 , showing a relaxation-type spectrum, different from the "magnetic plasma" of periodic metamaterials. Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials, with the advantage of enhanced absorption (40dB) and intelligent frequency selection even in a thin thickness (0.1 mm), could have potentials for electromagnetic attenuation and shielding. This work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials, as well as a novel strategy to precisely control the microstructure of random metamaterials.

show abstract

Section: Researchsupporting

confidence: 85%

“…Ac conductivity is also the function of frequency, usually explained by skin depth = (2/ 0 ) 0.5 [18]. The relationship between , j, and can be modified [16]:…”

Section: Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…[23][24][25][26] At present, the majority of attention is mainly paid to the ceramic-based or polymer-based bulk metacomposites. [27][28][29][30][31] However, fewer investigations are focused on the flexible membranous metacomposites. It is well known that the flexible materials have widespread and significant applications in electronics, sensors and energy storage.…”

Section: Introductionmentioning

confidence: 99%

Hydrosoluble Graphene/Polyvinyl Alcohol Membranous Composites with Negative Permittivity Behavior

Sun

Wang

Xin

et al. 2020

Macro Materials & Eng

Self Cite

View full text Add to dashboard Cite

In this work, a hydrosoluble matrix is used for the first time to prepare flexible membranous composites, in order to improve their environmental friendliness and simplify the processing. Modified graphene (GR) sheets are distributed in polyvinyl alcohol (PVA) solution to achieve flexible GR/PVA metacomposites. As graphene content increases, an interconnected graphene network is eventually formed among the PVA matrix, and the resulting composites present a conductor‐like behavior. Interestingly, the Drude‐like negative permittivity is obtained in the composites with 20 wt% graphene, which is ascribed to the plasma oscillation. Meanwhile, the absolute values of negative permittivity decrease by several orders of magnitude due to the moderate electron density of graphene. It is demonstrated that the negative permittivity is dependent on the inductive character. This work provides a novel and versatile approach based on water‐soluble matrices to prepare flexible membranous metacomposites, which can be applied in wearable cloaking, thin‐film capacitors, and flexible and stretchable devices.

show abstract

“…Therefore the investigation of metal‐free nanocatalysts with high activity and good stability for the ORR has attracted considerable interest. As one kind of porous carbon materials, hollow carbon sphere (HCS) owns the following characteristic features which are beneficial for using as an ORR electrocatalyst: (a) profuse porous structure;, (b) high specific surface area;, (c) high electric conductivity;, (d) high electrochemical durability ,,. The porous structure in HCS is conducive to the permeation of electrolyte, faster electron transfer and mass transport.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen and Phosphorus Co‐doped Hollow Carbon Spheres as Efficient Metal‐Free Electrocatalysts for the Oxygen Reduction Reaction

et al. 2018

View full text Add to dashboard Cite

Replacement of rare‐ and noble‐metal catalysts with earth‐abundant, low‐cost, stable, and efficient metal‐free catalyst substitutes is highly desirable, but full of challenges for the oxygen reduction reaction (ORR). Herein, N, P co‐doped hollow carbon spheres (N,P‐HCS) are prepared through a simple pyrolysis method, using hollow carbon spheres (HCS), melamine, and phytic acid (PA) as the C, N, and P sources, respectively. Compared to the N‐doped HCS (N‐HCS) and P‐doped HCS (P‐HCS), the N, P co‐doped sample exhibited much higher ORR catalytic activity. Moreover, in comparison with commercial Pt/C, the as‐prepared N,P‐HCS showed comparable ORR activity, but stronger endurance to methanol and higher durability in alkaline solution. The high performance of N,P‐HCS can be primarily ascribed to the large surface area, high conductivity, porous carbon structure, and high content of heteroatoms (N and P). Considering the excellent catalytic activity and durability, after further structural optimization, N,P‐HCS could be a promising metal‐free catalyst candidate for the ORR in fuel cells.

show abstract

Carbon aerogels towards new candidates for double negative metamaterials of low density

Cited by 110 publications

References 61 publications

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

Hydrosoluble Graphene/Polyvinyl Alcohol Membranous Composites with Negative Permittivity Behavior

Nitrogen and Phosphorus Co‐doped Hollow Carbon Spheres as Efficient Metal‐Free Electrocatalysts for the Oxygen Reduction Reaction

Contact Info

Product

Resources

About