Hydrogen storage and production by redox of iron oxide for polymer electrolyte fuel cell vehicles

摘要

Pseudo-storage of hydrogen and its recovery by redox of iron oxide have been proposed as a new method of the storage and supply of hydrogen for PEFC vehicles. Among the additives to iron oxide tested, Al, Cr, Zr, Ga and V were the effective elements enhancing both the reduction with H_2 (storage of H_2) and reoxidation with water (recovery of H_2) of the iron oxide (3Fe + 4H_2O →← Fe_3O_4 + 4H_2) at low temperatures (< 400℃). The additives moderated the sintering of iron oxide markedly with repeated redox cycles. It is suggested that another important role of additives is to activate H_2 and H_2O at the surface of iron oxide or to enhance the diffusion of O~(2-) as a result of the formation of compound oxides between the additive and iron oxide.