Activated carbon aerogels

Microporosity is a feature observed in many different materials (e g., activated carbons, aerogels, and xerogels). However, with regard to heterogeneous catalysis, zeolites are practically the only microporous catalysts used at present. The following chapter thus only addresses zeolites and their use in catalysis. 

In this process, oxidation of Mn(II) to Mn(III) and Mn(IV) resulted in the transformation of O3 into OH radicals. This capacity decreased with longer exposure, due to irreversible oxidation of Mn(II) to higher oxidation states. The pCBA oxidation rate increased in the presence of Mn-doped activated carbon aerogel compared to the Mn-doped organic aerogel, which the authors attributed mainly to the increase in surface basicity. The efficiency of the Mn-doped activated carbon aerogel to transform O3 into OH radicals was greater than that... 

Han TY-J, Worsley MA, Baumann TF, Satcher JH (2011) Synthesis of ZnO coated activated carbon aerogel by simple sol-gel route. J Mater Chem 21 330-333... 

Aerogel Carbon aerogel Activated carbon aerogel... 

Figure 12.6 The scheme of the preparation of aerogel, carbonized aerogel, and activated carbon aerogel.

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

However, the performance of a fuel cell with these carbon aerogels as DLs was around a factor of six lower than the performance of commercial electrodes. This was due mainly to the fact that the authors did not use additional electrolyte when depositing the catalytically active layer, thus causing reduced ionic conductivity between the catalyst (Pt particles) and the membrane. In addition, the MEAs with carbon aerogels performed poorly at high current densities because the Pt particles used were 10 times larger than the ones normally used [20]. 

Figure 1. Contour plots of IPSD as a function of Sbet for (a) fumed silicas, (b) silica gels and aerogels, and (c) activated carbons, carbon blacks, and graphitized carbons.

Figure 10.29 TGA data for UBH4 supported by different carbon supports, (a) UBH4 mixed with nonporous graphite, (b) LiBH4 incorporated into activated carbon. Curve (c) and (d) LiBH4 incorporated into carbon aerogel with average...

Apart from obvious dry cleaning applications, potential applications of C02-based microemulsions include (i) printed circuit board cleaning, (ii) extraction of contaminants from soils, (Hi) cleaning of polymers, foams, aerogels, porous ceramics, and laser optics, (iv) regeneration of activated carbon beds or catalysts, and (v) the separation of dyestuffs from textiles. 

This leads to a group of electrodes in which porous carbonaceous material itself provides the active materials. The carbon aerogels [18, 398, 399] are representative of this phenomenon. Storck have developed a mathematical model for the potential distribution in an activated-carbon packed-bed electrode [450]. An intraparticle porosity as well as an interparticle macroporosity are treated. It is a general problem... 

The same kinds of highly symmetric carbon systems for ECDLCs are also known for activated carbons [15, 249, 385], carbon blacks [33, 249], carbonaceous materials ( aerogels ) from phenol-formaldehyde resins via pyrolysis [18], and pyrolyzed PAN [430]. Another system, but with a rather low s,th> was built with two activated glassy carbon plates [240, 434] (cf. Section 7, group 6). 

Electrochemical Investigation of Carbon Aerogels and their Activated Derivatives... 

First results indicate a dependence of the surface capacitance of untreated carbon aerogels on their microstructure. Micro- and mesopores exhibit different storage capacitances (6.6 and 19.4 pF/cm in 1 M sulfuric acid, respectively).. An optimized thermal activation procedure of low density aerogels at 950°C in controlled CO2- atmosphere leads to an increase of the specific surface area and capacitance. On the other hand, the increase of the capacitive current after anodic oxidation in sulfuric acid is caused by electroactive surface groups, while the BET-surface area remains almost constant. 

In fig. 3 the applied voltage steps used for electrochemical activation for two different carbon aerogels are plotted. The capacitances of the samples derived via impedance spectroscopy at 8.25 mHz according to eq. 1 after each step are also shown. The physical and... 

EVOLUTION OF MICROPOROSITY UPON CO2-ACTIVATION OF CARBON AEROGELS... 

A large amount of microporosity that is hidden in carbon aerogels can be made accessible by activation methods without loss of monolithicity. To understand the differences between a very fine and a coarser aerogel with respect to microstructural changes upon pyrolysis and activation further investigations are necessary. 

Electrochemical investigation of carbon aerogels and their activated derivatives... 

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