Hydrogen adsorption properties of activated carbons with modified surfaces

Takagi, Hidenari; Hatori, Hiroaki; Yamada, Yoshio; Matsuo, Shuji; Shiraishi, Masashi

doi:10.1016/j.jallcom.2004.03.139

Cited by 86 publications

(51 citation statements)

References 22 publications

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“…15,16 Adsorption of H 2 on carbon materials has been studied by many authors. [17][18][19][20][21][22][23][24][25] But these investigations have been directed toward use of carbon materials as hydrogen storage materials, and not as catalyst support in PEMFCs.…”

Section: Introductionmentioning

confidence: 99%

Surface Self-Diffusion and Mean Displacement of Hydrogen on Graphite and a PEM Fuel Cell Catalyst Support

2009

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Quasielastic neutron scattering (QENS) measurements together with equilibrium molecular dynamic (EMD) simulations have been performed to investigate the surface interaction between hydrogen molecules and a carbon material commonly used in polymer electrolyte membrane fuel cells (PEMFC), called XC-72. Half a monolayer of molecular hydrogen was adsorbed on to the carbon material at 2 K. QENS spectra were recorded at the time-of-flight spectrometer IN5 at 40,45, 50, 60, 70, 80, and 90 K. Simultaneously the pressure was measured as a function of time to monitor the equilibrium surface coverage at each temperature. By using the Chudley and Elliott model for jump diffusion we found the diffusion coefficient at each temperature. At 350 K, a typical fuel cell temperature, the temperature function was extrapolated to a self-diffusion coefficient of 2.3 × 10 -7 m 2 /s. We simulated graphite in contact with hydrogen molecules using EMD simulation. We simulated the system at different temperatures from 70 to 350 K in 20 deg intervals and for five numbers of H 2 molecules N H 2 ) 50, 100, 150, 200, and 300. The graphite was made of 9 sheets of graphene in a sandwich. The surface self-diffusion was found from the mean-square displacement, and the values from EMD simulations are the same order of magnitude as the experimental values at 90 K, but systematically higher, probably due to the ideal surface. From EMD simulation, we also calculated the average time between adsorption and desorption events on the surface. This was used to find the mean displacement of the hydrogen molecules between adsorption and desorption. This result showed that H 2 molecules can move 80 Å at ambient temperatures and pressures, along the surface. Using these data, we conclude that catalyst support material in PEMFC contributes to the transport of reactant.

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Section: Introductionmentioning

confidence: 99%

Surface Self-Diffusion and Mean Displacement of Hydrogen on Graphite and a PEM Fuel Cell Catalyst Support

2009

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“…From recent reports it is apparent that various carbon materials made from carbon nanotubes, 9) graphite nanofibers, 10) and porous carbon materials are capable of storing hydrogen and have been considered for the next generation of energy systems. For example, porous carbon with a 3220 m 2 /g specific surface area is capable of storing 1.3 wt % of hydrogen at room temperature and 3570 MPa.…”

Section: )8)mentioning

confidence: 99%

Effect of potassium agents at activated carbon fabricated from rice husks on pore structure and hydrogen storage property

Toda

Akasaka

et al. 2013

J. Ceram. Soc. Japan

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Activated carbons were fabricated from carbonized rice husks (CRH) by the alkaline activation with KOH and K 2 CO 3 . The pore structure and stored hydrogen contents of activated carbons were investigated. The specific surface area of K 2 CO 3 and KOH activated samples were 1177, 1247 m 2 /g, respectively. The meso-pore volume of K 2 CO 3 activated sample was larger than KOH activated. On the other hands, the micro-pore volume of KOH activated sample was larger than K 2 CO 3 activated. These results indicated that meso-pore was preferentially developed by K 2 CO 3 activation and micro-pore was preferentially developed by KOH activation. The maximum storage hydrogen contents of activated carbon by KOH and K 2 CO 3 were 0.57 and 0.43 wt %, at 298 K and about 10 MPa, respectively. Thus, it suggests that micro-pore influence on stored hydrogen contents is greater than mesopore. Consequently, for the fabrication of activated carbon which is utilized for hydrogen storage, KOH is an effective activation agent more than K 2 CO 3 .©2013 The Ceramic Society of Japan. All rights reserved.Key-words : Activated carbon, Rice husk, Alkaline activation, Potassium hydroxide, Potassium carbonate, Pore structure, Hydrogen storage [Received February 1, 2013; Accepted March 18, 2013] Environmental destruction has increased the urgency to develop technologies for the recycling of various materials. The disposal of biomass waste from agricultural activities is an environmental problem. One of the solutions to this problem is to produce functional and reusable materials from agricultural wastes. Activated carbons fabricated from agricultural materials have been studied for use as functional materials. In particular, some activated carbons with nano-meter size pores-micropores-offer high performance because of their high specific surface areas. These activated carbons are prepared from various raw materials such as coal, 1) palm shell, 2) coffee waste, 3) and rice husks. 4) Such activated carbons are widely used because of their high adsorption properties.5) These approaches have been applied to hydrogen storage materials 6) and adsorbent materials for gases. 7),8)From recent reports it is apparent that various carbon materials made from carbon nanotubes, 9) graphite nanofibers, 10) and porous carbon materials are capable of storing hydrogen and have been considered for the next generation of energy systems. For example, porous carbon with a 3220 m 2 /g specific surface area is capable of storing 1.3 wt % of hydrogen at room temperature and 3570 MPa.11) The reports suggest the influence of the specific surface area on the hydrogen storage efficiency of the micropores. In activated carbons fabricated from agricultural wastes, it was reported that activated carbons with micro-pores in the pore structures were fabricated from the rice husks.12) Furthermore, it is well known that activated carbons with high micropore specific surface areas can be prepared through chemical activation with metallic compounds.13) Some researchers have used ...

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“…It is very complicate to compare all these results with those found with other doped carbonaceous materials used in hydrogen storage applications (i.e. activated carbons (Akasaka et al, 2011;De la Casa-Lillo et al, 2002;Takagi et al, 2004), nanotubes (Gao et al, 2010;Lamari et al, 2002;Schimmel et al, 2004;Surya et al, 2009) or nanofibers (De la Casa-Lillo et al, 2002;Kim et al, 2008)). The hydrogen storage capacity of Ni-doped carbon gels compared with other hydrogen storage systems is collected in Figure 13.…”

Section: Hydrogen Storagementioning

confidence: 99%