Improvement of Hydrogen Adsorption on Carbon Nanostructures

We present results of a study of the effect of various surface treatments on the adsorption properties of hydrogen on single-walled carbon nanotubes (SWNTs) and activated carbon. The alteration of the surface area by thermal and chemical treatments of SWNTs was studied by Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and nitrogen adsorption. The Horwath-Kawazoe (HK) method was applied to describe the increase of the surface area and of the pore volume of the SWNT samples. The surface treatments lead to substantially improvement of hydrogen adsorption at 77 K and 1 atm. The averaged heat of adsorption (enthalpy), estimated from a Dubinin-Astakhov (DA) analysis, was found to be about 3.6 and 4.2 kJ/mol for heat-treated and as-received SWNTs, respectively.