arXiv subjects

Thomas Leiner

Publications and source records attributed to Thomas Leiner.

2 recordsLinked to original sources

arXiv2024

Revealing trends in catalytic activity of adatoms for hydrogen adsorption on carbon: a case study of graphene and carbon nanotube

The increasing demand for sustainable energy solutions necessitates advancements in hydrogen storage technologies. This study investigates the hydrogen adsorption characteristics of graphene and a (8,0) carbon nanotube (CNT) decorated with adatoms of various elements. Using molecular dynamics (MD) simulations and the universal interatomic potential 'PreFerred Potential' (PFP) implemented in the Matlantis framework, we explore the hydrogen storage capabilities of these doped carbon structures at 77K. We analyze the adsorption efficiency based on the position of adatoms (top, bridge, and hollow sites) and find that the group II elements, such as calcium and strontium, exhibit significant hydrogen uptake. Additionally, light elements like lithium and sodium demonstrate enhanced gravimetric hydrogen storage due to their low atomic mass. Our findings provide insights into the potential of doped graphene and CNTs for efficient hydrogen storage applications.

cond-mat.mtrl-sci↗

arXiv2023

On energetics of allotrope transformations in transition-metal diborides via plane-by-plane shearing

Transition metal diborides crystallise in the $α$, $γ$, or $ω$ type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the $α$, $γ$, and $ω$ structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB$_2$ and MoB$_2$ possess the overall lowest sliding barriers among the investigated TMB$_2$s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants.

cond-mat.mtrl-sci↗