Anomalous hydrogen absorption on non-stoichiometric iron-carbon compound

Abstract: On the synthesis of nano-structural hydrogenated graphite by ball-milling under H2 atmosphere, iron contamination was mingled from steel balls during ball-milling. It is clarified by spectroscopic measurements that the mingled iron formed a non-stoichiometric iron–carbon (Fe–C) compound. The Fe–C phase was transformed to a well-ordered phase with H2 desorption at 450°C, suggesting that the hydrogen atoms were anomalously trapped at the Fe–C phase. With respect to hydrogen absorbing properties, the mingled iron enhanced the hydrogen capacity by about 50% compared with iron free hydrogenated graphite, where H/Fe was about 13mass%. Therefore, if the hydrogen absorption site originated in the Fe–C phase could be synthesized independently, it should be recognized as a promising hydrogen storage system. [ABSTRACT FROM AUTHOR]