Influence of MIL-101 doping by ionic clusters on hydrogen storage performance up to 1900 bar.

Ultra-high-pressure hydrogen-storage performance (up to 1900 bar) was investigated for mesoporous chromium terephthalate MIL-101 and its inclusion compounds containing ionic clusters [Re(4)S(4)F(12)](4-) and [SiW(11)O(39)](7-) within the porous framework. The maximum specific hydrogen uptake values (total) for MIL-101 are 12.3 (at 81) and 7.2 wt. % (at 293 K). Such unique measurement conditions allowed us to identify the density of the absorbed hydrogen directly from the excess sorption isotherm curves. The corresponding density values were found to be almost comparable at low temperature, but significantly different at ambient temperature, which indicated an increase of more than double in the number of hydrogen binding sites in the case of the inclusion compounds with rhenium clusters.