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Nanoarchitectonics of carbon-based electrodes via activated carbon/carbon composite xerogels by CO2
(2025-09-01)
Sirichan, Kasawan
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Kraiwattanawong, Kriangsak
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Bumroongsakulsawat, Palang
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Assabumrungrat, Suttichai
Carbon/carbon (C/C) composites, characterized by trimodal porous structures and highly tunable surfaces, offer promising prospects for electrochemical applications within the framework of nanoarchitectonics. However, recent research lacks systematic investigations into property-controlled performance. This study explores the effects of functional groups, surface area, and pore architecture in CO<inf>2</inf>-activated C/C composite xerogels synthesized from resorcinol-formaldehyde (RF) sol and cotton fibers (CFs). Increased activation time and CF content enhanced porosity, functional group density (O[sbnd]H and C[dbnd]O), and structural disorder. The macropores introduced by CFs facilitated deeper CO<inf>2</inf> penetration, thereby increasing meso‑ and microporosity, surface area, and specific capacitance. Electrochemical performance measured through cyclic voltammetry and charge/discharge analysis revealed that capacitance was governed primarily by surface area rather than pore geometry. Specific capacitance and surface area increased from 144 to 344 F g⁻¹ and from 575 to 1471 m² g⁻¹, respectively, under 0.5 A g⁻¹ discharge.
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Effect of starch addition on structural, electrical and thermal properties of delafossite CuAl0.9Fe0.1O2
(2017-12-01)
Pantian, Sarayut
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Sakdanuphab, Rachsak
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Sakulkalavek, Aparporn
In this study, starch was added to the delafossite CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> with the purpose of creating porosity in the structure. Increasing porosity contributes to a decrease in thermal conductivity, which increases the figure of merit (ZT) for thermoelectric properties. The results show that the porosity of the material increased as starch content was raised from 0 to 3 wt%. The thermal conductivity of CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> at room temperature decreased from 9.12 to 5.44 W/m.K as porosity increased from 12.0 to 43.4 vol%. The electrical conductivity decreased with increasing starch concentration, with the values ranging from 0.32 to 0.08 S/cm. Of all samples from 0 to 3 wt% starch, the sample with 1 wt% showed the highest ZT value. The increase of the ZT value resulted in a decrease in thermal conductivity due to sample porosity.
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HCl treatment on micropore and mesopore structures of carbon cryogels from resorcinol and formaldehyde
(2011-02-25)
Kraiwattanawong, Kriangsak
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Tamon, Hajime
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Praserthdam, Piyasan
The effect of HCl treatment on the porous properties of carbon cryogels synthesized from resorcinol and formaldehyde (RF) is investigated in this work. The treated and untreated carbon cryogels were analyzed with a nitrogen adsorption-desorption apparatus, scanning electron microscope (SEM) and high performance liquid chromatograph (HPLC). The results show that the HCl treatment can enlarge the micropore diameter which is advantageous to electric double layer capacitors, and can broaden the mesopore diameter, which is advantageous to mesoporous carbon supports of catalysts. The micropore volume, mesopore volume and weight loss of the carbon cryogel are not significantly changed by the HCl treatment. Moreover, SEM images and HPLC chromatograms support that the HCl treatment can promote the Ostwald ripening effect for RF carbon cryogels. © 2011 The Society of Chemical Engineers, Japan.
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Influence of solvent species used in solvent exchange for preparation of mesoporous carbon xerogels from resorcinol and formaldehyde via subcritical drying
(2011-02-01)
Kraiwattanawong, Kriangsak
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Tamon, Hajime
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Praserthdam, Piyasan
Carbon cryogels are dried by 3 days of freeze drying with 6 h of pre-freezing whereas the carbon xerogels are prepared by 1 day of subcritical drying in the selective range of synthesis condition, but the mesoporosity of carbon xerogels are not well controlled. This research is to study the influence of solvent species in the solvent exchange for the preparation of carbon xerogels cooperated by the evaporation drying and the vacuum drying. The good solvent for the high mesoporous properties of carbon xerogels is desirable in the wide range of synthesis condition. The carbon xerogels prepared from resorcinol and formaldehyde were characterized by the nitrogen adsorption apparatus and the field emission scanning electron microscope (FE-SEM). The results illustrate that the mesoporous carbon xerogels in the two subcritical dryings can be easily prepared by solvent exchange. Among the solvents, t-butanol allows the great results in the preparation of high mesoporous carbon xerogels and is well applied in the wide range of synthesis conditions. The FE-SEM images elucidate that the carbon xerogels dried by the vacuum drying contain the particles interconnection larger than the evaporation drying. © 2010 Elsevier Inc. All rights reserved.
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Control of mesoporous properties of carbon cryogels prepared from wattle tannin and furfural
(2008-12-01)
Kraiwattanawong, Kriangsak
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Mukai, Shin R.
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Tamon, Hajime
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Lothongkum, Anchaleeporn W.
Wattle tannin-furfural (TFu) carbon cryogels are synthesized by sol-gel polycondensation of wattle tannin with furfural by using sodium hydroxide (NaOH) as a catalyst, dried by freeze-drying technique and then pyrolyzed under inert atmosphere, respectively. The amounts of wattle tannin (T), furfural (Fu), NaOH (C) and distilled water (W) are changed for preparing the mesoporous TFu carbon cryogels. The mole ratio of tannin to catalyst T/C plays a crucial role for the synthesis of TFu organic and carbon cryogels. The results suggest that the T/C ratio should be above 0.25 but <1.0 to prepare the mesoporous and homogeneous cryogels. Although TFu carbon cryogels have the broad mesopore size distribution, the mesoporous structure is controllable by the synthesis conditions. The carbon cryogels possess the mesopore volume less than 0.56 cm<sup>3</sup>/g and the BET surface area less than 600 m<sup>2</sup>/g. Moreover, the ratio of catalyst to water C/W can be used to prepare the homogeneous and mesoporous carbon cryogels, and to control the mesopore radius of carbon cryogels in the range of 1.6-9.6 nm. © 2007 Springer Science+Business Media, LLC.
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Improvement of mesoporosity of carbon cryogels by acid treatment of hydrogels
(2008-11-01)
Kraiwattanawong, Kriangsak
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Mukai, Shin R.
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Tamon, Hajime
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Lothongkum, Anchaleeporn W.
Wattle tannin-furfural (TFu) gels are synthesized by the sol-gel polycondensation of wattle tannin with furfural by using sodium hydroxide as a catalyst and cured at 363 K. After cured, the TFu hydrogels are treated in hydrochloric acid (HCl) solutions with various variables as follows: aging temperature, HCl concentration and pH. TFu cryogels aged are then freeze-dried and pyrolyzed under an inert atmosphere to obtain TFu carbon cryogels. The TFu and carbon cryogels were characterized by N<inf>2</inf> adsorption and scanning electron microscope. The high HCl concentration yields the increase of mesopore volume almost twice especially at high temperature and the mesopore size distribution can be greatly developed sharper and narrower when the high concentration of HCl or/and the high temperature are used. Moreover, this method is the versatile approach for developing the mesopore structure of the low and high porous TFu hydrogels and has no serious problem of weight loss after treatment. © 2008 Elsevier Inc. All rights reserved.
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Improvement of mesopore structure of resorcinol and formaldehyde carbon cryogels by acid solution
(2008-01-01)
Kraiwattanawong, K.
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Kitchaiya, P.
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Neramittagapong, A.
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Praserthdam, P.
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Tamon, H.
Resorcinol and formaldehyde (RF) carbon cryogels are prepared by sol-gel polycondensation by using sodium carbonate (C) as a catalyst with water (W) as solvent, immersed in acid solution, hydrochloric acid (HC1), dried by freeze-drying technique and then carbonized under inert atmosphere, respectively. Compared with their carbon precursors, both V<inf>mes</inf> and mesopore size distributions of all carbon cryogels can be developed since the pore shrinkage is the crucial role in the change of pore structure of carbon gels. HC1 may promote the strength of small pore structure and increase the pore shrinkage of large pore structure. Consequently, the treatment of HC1 does not only enhance the partial collapse of large pore structure, the treatment also increases the strength of small pore structure to inhibit the shrinkage of this structure during carbonization as well. © 2008 Trans Tech Publications, Switzerland.
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Preparation of carbon cryogels from wattle tannin and furfural
(2007-01-05)
Kraiwattanawong, K.
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Mukai, S. R.
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Tamon, H.
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Lothongkum, A. W.
Wattle tannin-furfural (TFu) hydrogels were synthesized by the sol-gel polycondensation of wattle tannin with furfural by using three types of base catalysts (NaOH, Na<inf>2</inf>CO<inf>3</inf> and NaHCO<inf>3</inf>). TFu cryogels were prepared by freeze drying of the hydrogels and TFu carbon cryogels were obtained by pyrolysis of the cryogels in an inert atmosphere. The TFu and carbon cryogels were characterized by N<inf>2</inf> adsorption and scanning electron microscope (SEM). The effect of catalysts on porous properties of carbon cryogels resulted in different ways: (1) NaOH enhances increasing mesopore volumes and surface area of carbon cryogels and (2) Na<inf>2</inf>CO<inf>3</inf> and NaHCO<inf>3</inf> cause decreasing those of carbon cryogels. The TFu and carbon cryogels prepared by using NaOH as a catalyst possessed large mesopore volumes comparing with micropore volumes. Even though the TFu cryogels have surface area and mesopore volumes smaller than the resorcinol-formaldehyde (RF) cryogels, the carbon cryogels have unique porous properties differed from the RF carbon gels. The properties are summarized as follows: (1) the mesopore volume changes insignificantly after pyrolysis, (2) the pore radius is increased after pyrolysis and (3) micropores are not greatly developed during pyrolysis. © 2006 Elsevier Inc. All rights reserved.

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