Hydrogen storage in pressed nanophase diamond powder

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The nanophase diamond has been studied as an alternative for solid hydrogen storage, first by the affinity of carbon and hydrogen, and second because of the high volumetric storage of this material due to the physical and chemical effects at the nanoscale level. It is a potential solid storage medium by its high surface area and high surface energy, and exhibits good characteristics for adsorption as evidenced by the nitrogen adsorption curves. This thesis describes how to treat the nanophase diamond powder surface to achieve a higher hydrogen concentration, and increase desorption to adsorption ratio by the incorporation of metals, including from alkali and transition groups, and a metalloid. This metal-support cooperation is essential to develop a bifunctional catalysis as a fast diffusion mechanism for transferring the adsorbed species from the catalyst site to the support surface and vice versa. The effect of temperature and pressure variation to increase hydrogen storage in the nanodiamond structure is also higher for treated surfaces. The physical and chemical modifications of the nanophase diamond powder enhanced its catalytic and adsorptive properties. The surface treatment results in a net storage of 3.2 wt% with a recovery of 72% of the adsorbate at 750°C.