Transition metal (TM) atoms bound to fullerenes are proposed as adsorbents for high density, room temperature, ambient pressure storage of hydrogen. ${\mathrm{C}}_{60}$ or ${\mathrm{C}}_{48}{\mathrm{B}}_{12}$ disperses TMs by charge transfer interactions to produce stable organometallic buckyballs (OBBs). A particular scandium OBB can bind as many as 11 hydrogen atoms per TM, ten of which are in the form of dihydrogen that can be adsorbed and desorbed reversibly. In this case, the calculated binding energy is about $0.3\mathrm{eV}/{\mathrm{H}}_2$, which is ideal for use on board vehicles. The theoretical maximum retrievable ${\mathrm{H}}_2$ storage density is $\sim 9\mathrm{wt}\%$.

• Received 8 December 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.155504