First-principles modeling of the polycyclic aromatic hydrocarbons reduction

TL;DR

This study uses density functional theory to investigate the reduction process of nanographene molecules by hydrogen, revealing symmetry-related limits and changes in binding energy that explain experimental hydrogenation constraints.

Contribution

It provides a first-principles analysis of hydrogenation limits in nanographenes, highlighting symmetry conflicts and energetic factors affecting reduction.

Findings

Hydrogenation limits are linked to symmetry conflicts between nanographenes and hydrogen pairs.

Binding energy increases during reduction, influencing hydrogenation extent.

Symmetry considerations explain experimental hydrogenation limitations.

Abstract

Density functional theory modelling of the reduction of realistic nanographene molecules (C42H18, C48H18 and C60H24) by molecular hydrogen evidences for the presence of limits in the hydrogenation process. These limits caused the contentions between three-fold symmetry of polycyclic aromatic hydrocarbon molecules and two-fold symmetry of adsorbed hydrogen pairs. Increase of the binding energy between nanographenes during reduction is also discussed as possible cause of the experimentally observed limited hydrogenation of studied nanographenes.