Hydrogen Storage in Organometallic Structures Grafted on Silsesquioxanes

Using density functional theory we show that a recently synthesized silsesquioxanes (SQ) nano complex [RSiO 3/2 ] n with R = −C 5 H 5 provides a novel material for hydrogen storage. Grafting cyclopentadienyl on SQ totally changes its electronic structure and chemistry: cyclopentadienyl becomes a reactive site where a transition metal atom (e.g., Sc) can be doped to serve as an effective adsorption site for hydrogen molecules. This nano complex has the following advantages: (1) The storage capacity in the fully grafted case is 5 wt % where hydrogen is bound molecularly with a binding energy of about 0.6 eV/H 2 molecule. (2) The structure of SQ itself is stable. Our study shows for the first time that the functionalized SQ complexes can be an effective and practical material for hydrogen storage.