Hydrogen adsorption on Ti containing organometallic structures grafted on silsesquioxanes

The adsorption of hydrogen molecule on a novel structure of Ti containing organometallic complexes grafted on silsequioxanes (SQ, H8Si8O12) was investigated by means of DFT method. The hydrogen adsorption properties of the complex structures TiRH7Si8O12 (R = C4H3, C5H4, C6H5) keep almost the same as that of corresponding Ti containing organometallic complexes. Moreover, these complex structures can avoid the problem of transition metal clustering which is a disadvantage for hydrogen adsorption. The maximum number of hydrogen molecules adsorbed was still determined by 18 electron rule, that is to say 5, 4, and 4 H-2 molecules for TiRH7Si8O12 with R = C4H3, C5H4, and C6H5, respectively. At the same time, all the average binding energy of H-2 is located in 0.2-1.0 eV, which is an advantage for hydrogen storage at ambient conditions. Therefore, the materials studied here may provide some enlightenment for developing new types of hydrogen storage materials.