Hydrogen adsorption on carbon nanocone material studied by thermal desorption and photoemission

The hydrogen adsorption/desorption behaviour on carbon nanocones was studied by temperature-programmed desorption, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. X-ray photoelectron spectroscopy shows a small shift of about 0.1 eV of the C1s core level to higher binding energy. The work function is found to decrease with increasing hydrogen exposure; after a hydrogen exposure of 9000 L a decrease of 0.3 eV was observed. The maximum of the desorption peak is located near a temperature of 250 K. The large peak width shows that the desorption process may not be characterized as a simple first or second order process. Most likely, the spectrum consists of desorption from sites of different geometry as well as being influenced by adsorbate–adsorbate interactions.