H2 Transformations on Graphene Supported Palladium Cluster: DFT-MD Simulations and NEB Calculations

Abstract

Molecular dynamics simulations based on density functional theory were employed to investigate the fate of a hydrogen molecule shot with different kinetic energy toward a hydrogenated palladium cluster anchored on the vacant site of a defective graphene sheet. Hits resulting in H2 adsorption occur until the cluster is fully saturated. The influence of H content over Pd with respect to atomic hydrogen spillover onto graphene was investigated. Calculated energy barriers of ca. 1.6 eV for H-spillover suggest that the investigated Pd/graphene system is a good candidate for hydrogen storage.

Empathes: A general code for nudged elastic band transition states search

“…Empathes interfaced with Siesta to successfully unravel the spillover mechanism of hydrogen atoms from Pd to graphene in a system formed by a Pd 4 cluster anchored on a C-vacancy of the graphene sheet. [14] [Table 1 about here. ]…”

Computational investigation of isoeugenol transformations on a platinum cluster – I: Direct deoxygenation to propylcyclohexane

“…This because, in addition to the ease of hydrogen fragmentation on the cluster, free diffusion of the hydrogen atoms through the catalyst could be hypothesized. To corroborate these inferences, demonstrated for most of metal systems [44,45], fragmentation and diffusion tests were carried out considering one H 2 molecule on the Pt 10 cluster, in the following represented as Pt 10 H 2 species.…”

“…This implies that the hydrogen atoms can be arranged in any configuration on the cluster. It is finally to be underlined that, as it happens in the case of a large number of metal clusters [44,46,47], the fragmentation of H 2 is the cause of the decrease of one unit of the spin quantum number observed in the Pt 10 2 H systems, being this occurrence correlated to electron spin coupling phenomena. This value, which is quite high if one looks at adsorption studies of simple alkenes on metal clusters [49], is indeed justified by the presence of the aromatic component which strongly interacts with the cluster.…”

Supported Metal Nanohydrides for Hydrogen Storage

“…However, this mechanism has been analyzed in detail for the case of Pd nanoparticles supported on graphene by performing accurate atomistic dynamical simulations, and its validity has been questioned, because of the existence of large spillover barriers. , Sizable barriers have also been predicted from calculations for other supported transition metal clusters. − Palladium is, in fact, a promising metal for applications related to hydrogen storage because it can absorb large amounts of hydrogen in the form of palladium hydrides . For this reason, the adsorption of hydrogen on free Pd nanoclusters − and on various types of carbon materials functionalized with palladium has been investigated. ,,− …”