Hydrogen adsorption on two-dimensional germanene and its structural defects: an ab initio investigation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Germanene, a 2D material analogous to graphene, is a promising candidate for electronic applications.
• Understanding hydrogen adsorption is crucial for functionalizing germanene and predicting its behavior in hydrogen-rich environments.

Purpose of the Study:

• To investigate the adsorption mechanisms of hydrogen on pristine germanene.
• To explore the impact of hydrogen adsorption on germanene's local structure and electronic properties.
• To characterize the properties of various germanene defects.

Main Methods:

• Ab initio calculations
• Density Functional Theory (DFT) for converged calculations
• Analysis of adsorption sites, structural modifications, and defect formation energies

Main Results:

• Identified nearly degenerate adsorption sites (HT1 and HT2) for hydrogen on pristine germanene, with HT1 being the most stable.
• Observed local structural distortions in germanene upon hydrogen adsorption.
• Characterized four types of germanene defects: Stone-Wales, two divacancies, and a pentagon-heptagon linear defect.
• Determined the pentagon-heptagon linear defect exhibits the lowest formation energy, a novel finding.

Conclusions:

• Pristine germanene exhibits specific hydrogen adsorption preferences and undergoes structural changes.
• The study provides the first investigation into localized surface curvature and zero-point energy of hydrogen on 2D germanene.
• Germanene defects significantly influence its properties, with the pentagon-heptagon linear defect being the most energetically favorable to form.