Possibilities of atomic hydrogen storage by carbon nanotubes or graphite materials

Abstract

Atomic hydrogen storage by carbon nanotubes (CNTs) and highly oriented pyrolytic graphite (HOPG) has been studied using a flow catalytic reactor and an ultra-high vacuum surface science apparatus including scanning tunneling microscope (STM), respectively. Defect sites on CNTs as adsorption sites of atomic hydrogen are introduced by oxidation pretreatment using La catalyst. Pd catalysts are then deposited on CNT surfaces for dissociation of H 2 into atomic hydrogen, which spills over to the defect sites. In the best case, 1.5 wt% of hydrogen is stored in the defective CNT with Pd particles at 1 atm and 573 K. In temperature programmed desorption (TPD) experiments, H 2 starts to desorb at 700-900 K depending on the annealing temperatures of CNTs prior to hydrogen storage. On the HOPG surface, hot atomic hydrogen produced by dissociation of H 2 using tungsten wire desorbs from graphite terraces at 400-700 K, which is much lower than that on CNTs. It is possible that one can decrease the desorption temperature by changing the method of H 2 dissociation. q

X-ray Photoelectron Spectroscopy Study of Cobalt Supported Multi-walled Carbon Nanotubes Prepared by Different Precursors

“…8, the peak of (b) obtained from CoMWCNTs decorated with cobalt acetate (Co(CH 3 COO) 2 ) revealed at 778 eV. According to the reference [10], this peak may be considered as Co(C 5 H 5 )) 2 or dibuthyldithiocarbamate molecular.…”

“…As an alternative to the usual functionalization techniques that are used to increase the reactivity of the CNT surface, CNT can be decorated with metal nanoparticles. For example, Pd decorated CNTs become sensitive to H 2 [10]. Metal clusters have a broad range of diverse structures and can provide a wide range of reactivity with different species [11].…”

Heat of adsorption and binding affinity for hydrogen on pitch-based activated carbons

“…Reversible adsorption of hydrogen on carbonaceous materials has been attracting much interest, as it can be realized from the pioneering works reporting the hydrogen adsorption behavior of carbon nanotubes, graphite fibres, activated carbon, etc. [2][3][4][5][6][7][8]. Previous studies by several researchers show that the storage capacity of these materials is greatly influenced by the surface area, pore volume and pore size distribution [4,9,10].…”

Calculations of adsorption energies, coadsorptions, and diffusion barriers of H atoms, and the H2 formation on a nanographene surface (coronene)

“…Polycyclic aromatic hydrocarbons (PAHs) play an important role in mesoporous activated carbons because they provide adsorption sites for radicals generated during thermal processes . There exist also the possibility of using carbon nanostructures (nanographenes, e.g., coronene) formed of PAHs and graphenes as storage materials of atomic hydrogen . In addition, PAHs are very relevant components of petroleum and may act as a trap for radicals produced in the cracking of hydrocarbons .…”