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

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(2)O reversible arrow Fe3O4 + 4H(2)) at low temperatures (< 400°C). 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 H2O at the surface of iron oxide or to enhance the diffusion of O2- as a result of the formation of compound oxides between the additive and iron oxide. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.