Using density functional theory, we designed novel cluster structure units with large surface areas for hydrogen storage through the surface functionalization of a stable Si12C12H24 nanocage with -CONH2 organic molecules and Li atoms. Two structures, namely, Si12C12H12\(CONHLi)(12) and Si12C12H12(CONLi2)(12), are proposed. The structures are stable at room temperature and show suitable hydrogen adsorption energies. Modification can enlarge the surface area of the two structures compared with the original cluster. In addition, the O and N anions participate in the adsorption of H-2 molecules in addition to the Li cations. The average hydrogen binding energy for Si12C12H12(CONHLi)(12)center dot 82H(2) is 0.135 eV/H-2 and the average hydrogen binding energy for Si12C12H12(CONLi2)(12)center dot 84H(2) is 0.134 eV/H-2 when these cluster structure units reach their maximum H-2 uptake capacity. The gravimetric hydrogen percentages are 13.18 and 12.60 wt%, respectively. With such a structural unit, a suitable linker allows the assembly of metal organic framework-like porous materials that display satisfactory hydrogen storage properties at room temperature. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.