Carbon aerogels as broadband non-reflective materials

Merzbacher, Celia I.; Meier, Steven R.; Pierce, Jeremy R; Korwin, Michelle L.

doi:10.1016/s0022-3093(01)00455-0

Cited by 59 publications

(42 citation statements)

References 12 publications

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“…The amorphous carbon aerogel sample appears completely opaque before heating, owing to its strong broadband absorbance (13). The material becomes highly transparent following laser heating and was observed to transmit a large amount of incident light in comparison with the amorphous precursor (Fig.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of a nanocrystalline diamond aerogel

Pauzauskie

Crowhurst

Worsley

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laserheated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Timeresolved photoluminescence measurements of recovered material reveal the formation of both nitrogen-and silicon-vacancy pointdefects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.gigapascal | nanomaterials | phase transition | photonics | qubit A erogels are a fascinating class of high surface-area continuous solids with a broad range of both commercial and fundamental scientific applications (1-8). Both crystalline and amorphous structures have been synthesized. Amorphous carbon aerogel in particular has received a considerable amount of attention in recent years owing to its low cost, electrical conductivity, mechanical strength, and thermal stability (9). Numerous applications have been explored for this material including water desalination (10), electrochemical supercapacitors (11), as well as both thermal (12) and optical (13) insulation. Impressive advances have been made in the case of polycrystalline aerogels through the oxidative aggregation of chalcogenide quantum dots that preserve spectral signatures of quantum confinement (14). Furthermore, recent high-pressure, high-temperature (HPHT) experiments with mesoporous silica and periodic carbon have been employed to produce mesoporous coesite (15, 16) and diamond (17) structures.Despite much progress in achieving phase transitions in mesoporous materials, the transition from an amorphous to a crystalline phase in carbon aerogel materials has remained a challenge. The extremely low density and irregular pore structure in aerogel materials make preventing pore collapse a formidable obstacle. Such a nondestructive transition would nevertheless be desirable, because a porous, three-dimensional self-supporting structure consisting of diamonds would have unprecedented optical, thermal, and chemical properties while still maintaining the inherent advantages of aerogel morphology. For instance, diamond aerogel promises a widely tunable optical index of refraction (∼1 < n < 2.4) for antireflection coatings, biocompatibility, chemical doping, potentially enhanced thermal conduction, as well as electrical field emission applications while still maintaining the low-density, high surface area and self-supporting aerogel morphology. Such a material is particularly intriguing in light of the numerous scientific and technological applications of conventi...

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of a nanocrystalline diamond aerogel

Pauzauskie

Crowhurst

Worsley

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…In the case of low RF concentrations, this produces small, smooth, fractal aggregates of gel particles [9] with wide pore size distributions (PSDs). [9,38] In contrast, when using an acidic catalyst solution with high RF concentrations, the fractal aggregates are no longer observed and very narrow PSDs (6±7 nm) are obtained. [9] An example on these effects of the catalyst type and ratio is shown in Figure 1.…”

Section: Materials and Initial Solution Recipesmentioning

confidence: 98%

“…[2] The addition of these metals increases the meso-and macropore volumes (and results in the highest possible total pore volumes in the case of small concentrations of Pt). [2] In addition to the alkaline catalysts, dilute acidic catalyst solutions (e.g., HClO 4 [9,39] or HNO 3 [38] )…”

Section: Materials and Initial Solution Recipesmentioning

confidence: 99%

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Preparation and Properties of Resorcinol–Formaldehyde Organic and Carbon Gels

Al‐Muhtaseb¹,

Ritter²

2003

Advanced Materials

986

795

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A brief overview on the preparation and properties of resorcinol–formaldehyde organic and carbon gels reveals very interesting features about their structural and performance characteristics. The resulting nanostructure was very sensitive to the various synthesis and processing conditions. This leads to a remarkable potential for designing and tailoring these materials to fit specific applications. Based on step‐by‐step comparisons of the published studies, approximate generalizations on the specific roles the synthesis and processing conditions play on the final properties are provided. Overall, resorcinol–formaldehyde organic gels undergo two main stages during synthesis. The first stage is associated with the preparation of the sol mixture, and the subsequent gelation and curing of the gel. The second stage is associated with the drying of the wet gel. The most important factors that affect the properties of the organic gel during the first stage are the catalyst concentration, the initial gel pH, and the concentration of the solids in the sol. The most important factors that affect the properties of the organic gel during the second stage are the drying procedure (e.g., super‐ or subcritical drying), and the difference between the surface tensions of the solvent before and after drying. The corresponding resorcinol–formaldehyde carbon gels are produced from the organic gels during a third stage, which is associated with carbonization or activation. Depending on the conditions, carbonization and activation both impact the structural and performance characteristics significantly.

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“…Examples of other non-metal catalysts are acetic acid, hydrochloric acid, nitric acid, and hexamethylenetetramine. [11][12][13] The quality determining factor of carbon aerogels is also pyrolysis, which converts organic aerogels into carbon aerogels. Generally pyrolysis is responsible for changing the specific surface area and conductivity of aerogels.…”

Section: Introductionmentioning

confidence: 99%

Lithium-Catalyzed Carbon Aerogel and Its Possible Application in Energy Storage Materials

Ciszewski

Szatkowska

Koszorek

2017

Journal of Elec Materi

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A lithium-based catalyst for carbon aerogel compounds and carbon nanotubes synthesis was used. Lithium hydroxide-catalyzed and CNT-modified carbon aerogel was compared to traditionally synthesized sodium carbonate-catalyzed carbon aerogel, as well as to the same material modified with CNT to evaluate the real effect of lithium hydroxide addition. Enhancement in the specific surface area from 498 m 2 /g to 786 m 2 /g and significant change in pore size distribution were observed. Low temperature, supercritical drying in carbon dioxide was used to prepare an organic aerogel with subsequent pyrolysis in an inert gas flow to convert it into carbon aerogel. The as-obtained material was examined with respect to energy storage applications, i.e. symmetric hybrid supercapacitors. It was shown that lithium hydroxide was responsible for shorter gelation time, increased specific surface area, and a greater number of micropores within the structure. For both reference materials prepared using sodium carbonate, quite different data were recorded. It was presented that the proper choice of carbon matrix should combine both high specific surface area and appropriate pore size distribution. High surface area and a relatively large number of micropores were responsible for specific capacity loss.

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Carbon aerogels as broadband non-reflective materials

Cited by 59 publications

References 12 publications

Synthesis and characterization of a nanocrystalline diamond aerogel

Synthesis and characterization of a nanocrystalline diamond aerogel

Preparation and Properties of Resorcinol–Formaldehyde Organic and Carbon Gels

Lithium-Catalyzed Carbon Aerogel and Its Possible Application in Energy Storage Materials

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