Dissociation of hydrogen molecules on the clean and hydrogen-preadsorbed Be(0001) surface

TL;DR

This study uses first-principles calculations to analyze hydrogen molecule dissociation on clean and preadsorbed Be(0001) surfaces, revealing lower energy barriers with preadsorption and detailed dissociation behaviors.

Contribution

It provides new insights into hydrogen dissociation mechanisms on Be(0001), including the effects of preadsorbed hydrogen and the dissociation energy barriers.

Findings

Dissociation barrier on clean surface is 0.75 eV.

Preadsorbed hydrogen reduces the barrier to 0.50 eV.

Hydrogen atoms prefer not to cluster or penetrate subsurface sites.

Abstract

Using first-principles calculations, we systematically study the potential energy surfaces and dissociation processes for hydrogen molecules on the clean and hydrogen-preadsorbed Be(0001) surfaces. It is found that the most energetically favored dissociation channel for H2 molecules on the clean Be surface is at the surface top site, with the minimum energy barrier of 0.75 eV. It is further found that after dissociation, hydrogen atoms do not like to cluster with each other, as well as to penetrate into subsurface sites. For the hydrogen-preadsorbed Be(0001) surface, the smallest dissociation energy barrier for H2 molecules is found to be 0.50 eV, which is smaller than the dissociation energy barrier on a clean Be(0001) surface. The critical dependence of the dissociation energy barriers for H2 molecules on their horizontal distances from the preadsorbed hydrogen atom is revealed. Our studies well describe the adsorption behaviors of hydrogen on the Be(0001) surface.