Hydrogen adsorption on graphite (0001) surface: A combined spectroscopy–density-functional-theory study.

The adsorption of H/D atoms on the graphite (0001) surface is investigated by means of both high-resolution electron-energy loss spectroscopy (HREELS) and periodic first-principle density-functional theory. The two methods converge towards two modes of adsorption: adsorption in clusters of about four hydrogen atoms and adsorption in pairs of atoms on contiguous carbon sites. The desorption energies estimated from the calculated dissociation energies range from 8 to 185 kJ mol^-1 leading to an estimated surface coverage at saturations of 30–44 at. %. These results are compared with previous thermal desorption spectroscopy results. New HREEL signal assignments are proposed based on quantum calculations. [ABSTRACT FROM AUTHOR]