Electronic properties and hydrogen storage capacity of the -Ge nanostructures

The stability and electronic properties of alpha Ge nanocrystals and nanoflakes were studied in the [111] and [110] crystallography directions. The findings showed that the electronic properties of the alpha Ge flakes depend on crystallographic directions, shape, and system size, with well-behaved trends observed as the structure grows. It is demonstrated that the 111-alpha Ge systems can store one hydrogen molecule per Ge-ring on their surface, with significantly improved capacity when considering the adsorption of Nb atoms on the alpha Ge surface. The Nb@alpha Ge system can store at least three H-2 molecules per Nb atom, with an estimated hydrogen weight percent of 6.11%. An applied strain of about 1% decreased the binding energy by similar to 20%, indicating that strain can be an important alternative for engineering the bond between H-2 and the Nb@alpha Ge surface. Based on these findings, the alpha Ge surface is identified as a promising material for hydrogen storage, particularly with Nb atoms adsorbed on its surface, paving the way for further studies on the practical applications of 2D-alpha-Ge in this field.