The effects of a hydrogen pair in the electronic structure of the FCC Iron containing a vacancy

D. REY SARAVIA D, S. SIMONETTI, G. BRIZUELA, A. JUAN

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2010 vol. 35 p. 5957 - 5962

0360-3199

Fuel cell vehicles have been identified as the personal transportation technology of the future because of their high efficiency and very low emissions. To achieve the goal of road ready fuel cell vehicles, great strides must be made in the development of fuel cells, hydrogen production and hydrogen storage technologies, that includes metal–H interaction studies and safety considerations. The interaction between two-hydrogen atoms and a g-Fe structure containing a vacancy has been studied using a cluster model and a theoretical method. For the study of the sequential absorption, the hydrogen atoms were positioned in their energy minima configurations, near the vacancy. The interactions mainly involve Fe 4s–H 1s atomic orbitals. The contribution of Fe 4p and Fe 3d orbitals is much less important. The Fe–Fe bond is weakened as new Fe–H–H and H–H pairs were formed. The effect of H atoms is limited to its first Fe neighbors. The Fe–Fe bond strength decreases with the introduction of the H atoms. Fe–H bonding is achieved at expense of weakening the metal–metal nearest bonds. There is not a real bond between the H atoms but some H–H interaction is observed. The detrimental effect of H atoms on the Fe–Fe bonds can be related to one of the aspect of embrittlement in g-Fe.