THE EFFECT OF H ON THE ELECTRONIC STRUCTURE OF AN Fe(110)–Pd(100) INTERFACE

Abstract

The ion-driven mechanism in hydrogen permeation is substantially modified when iron is coated with palladium. A detailed knowledge of the electronic structure at the metal–metal interfaces is a prerequisite for understanding the process of H permeation. We have selected two low-Miller-index surfaces as a simple model for the interface. The system under consideration has 148 metallic atoms forming an Fe–Pd cluster distributed in six metallic layers. We have investigated the interaction of atomic hydrogen with the Fe (110)– Pd (100) interface using the semiempirical atom superposition and electron delocalization (ASED-MO) method. The changes in the electronic structures, density of states (DOS) and crystal overlap orbital population (COOP) in two different Fe–Pd interfaces were compared with the bulk ground states of both metals. The interfacial Fe–Pd distance results in about 1.74 Å, whereas for the Fe–Pd first neighbors distance it is about 1.85 Å. An important conclusion is that the metal–metal bonds at the interface are stronger than those bonds in the pure metal bulk. A favorable metal adhesion is observed, as revealed by the energetic stabilization of the composite metal system. H is stabilized near the FePd interface and stopped at the first Pd layer. A H–metal bond is developed with both Fe and Pd atoms while Fe–Pd bonding at the interface remains unaltered.