Influences of Al doping on the electronic structure of Mg(0001) and dissociation property of H2

TL;DR

This study uses density functional theory to analyze how aluminum doping affects the electronic structure and hydrogen dissociation properties of Mg(0001) surfaces, revealing changes in surface relaxation, work function, and dissociation energy barriers.

Contribution

It provides detailed insights into the electronic and dissociation behavior modifications caused by Al doping on Mg(0001), a novel investigation into corrosion resistance mechanisms.

Findings

Al doping causes surface relaxation from expansion to contraction.

Doping increases the work function and alters electronic states around the Fermi level.

The dissociation energy barrier of H2 increases with Al doping, especially at the first layer.

Abstract

By using the density functional theory method, we systematically study the influences of the doping of an Al atom on the electronic structures of the Mg(0001) surface and dissociation behaviors of H2 molecules. We find that for the Al-doped surfaces, the surface relaxation around the doping layer changes from expansion of a clean Mg(0001) surface to contraction, due to the redistribution of electrons. After doping, the work function is enlarged, and the electronic states around the Fermi energy have a major distribution around the doping layer. For the dissociation of H2 molecules, we find that the energy barrier is enlarged for the doped surfaces. Especially, when the Al atom is doped at the first layer, the energy barrier is enlarged by 0.30 eV. For different doping lengths, however, the dissociation energy barrier decreases slowly to the value on a clean Mg(0001) surface when the doping layer is far away from the top surface. Our results well describe the electronic changes after Al-doping for the Mg(0001) surface, and reveal some possible mechanisms for improving the resistance to corrosion of the Mg(0001) surface by doping of Al atoms.