Hydrogen penetration mechanism through C and CH pre-covered Pd(100) surface: A density functional theory study

This paper investigates the role of carbon-containing impurities (i.e. C, C + H, CH, and CH + H) playing in hydrogen diffusion into Pd(100) subsurface. Energetics and structures for adsorptions and absorptions of hydrogen were explored with variational coverages and locations of adsorbates by density functional theory, and then minimum energy pathways were cautiously searched out by climbing image nudged elastic band method. Surface relaxation and reconstruction effects were also concerned. Quantum simulations reveal that C and CH strongly bond to hollow site and lead to charge density redistribution and structural change of Pd(100) surface, and thus predominantly affect hydrogen penetration behavior.