DFT study on interaction of hydrogen with Pd(1 1 1)

The interaction of hydrogen atoms with Pd(1 1 1) surface is studied with density functional theory (DFT) method. Various coverages ranging from 0.25 to 2.00 monolayer (ML) are considered. Particular attention is paid to the thermodynamics and kinetics of the adsorption or absorption processes and to the structural and electronic properties. The results show that the threefold hollow sites, FCC and HCP are most energetically favorable. The diffusion processed in the same layer is more preferential than the penetration processed in two different layers. For the coverages more than 1.00 ML, it is predicted that the additional hydrogen easily penetrates into subsurface. PDOS research shows that the interaction of hydrogen atoms with Pd leads to a splitting of d electron density of the outmost Pd(1 1 1) and to a gradual decrease of d band center of surface Pd atoms with coverages increasing.