Modified iron oxides with single- or double-metal-cation-additive (Fe-Mo, Fe-Al, Fe-Mo-Ni, and Fe-Mo-Al) for hydrogen storage were prepared by an impregnation method using Fe powder as a starting material and their performances of hydrogen storage were investigated in detail. The results show that among all 4 cation-modified samples, the Mo-modified sample is the most favorable one; for example, the temperature of H₂ formation for the Fe-Mo was obviously decreased from 500 ℃ before the addition of Mo to 290 ℃ after the addition of Mo, while the rate of H₂ formation was remarkably enhanced from 50 μmol•min^－1•Fe-g^－1 to 325 μmol•min^－1•Fe-g^－1 (average value of 10 cycles) at 300 ℃; the average capacity of hydrogen storage reached 4.53 wt%, closed to theoretical value 4.8 wt%; the cyclic stability of re-oxidation increased with increasing the number of cycles. In addition, the results of SEM and BET surface area show that the kind of metal cation added to Fe powder is more important for the samples to be modified.

Key words: modified iron oxide, Fe-powder, metal cation Mo, Al, Ni additive, hydrogen storage property, cyclic stability