Plasmonic enhancement of molecular hydrogen dissociation on metallic magnesium nanoclusters

TL;DR

This study investigates how plasmonic magnesium nanoclusters can generate energetic hot electrons to promote hydrogen dissociation and evolution, offering promising insights for light-driven hydrogen storage and release.

Contribution

It provides a detailed theoretical analysis of magnesium nanoclusters' electronic and catalytic properties, highlighting their potential in plasmonic hydrogen reactions, which was less explored compared to noble metals.

Findings

Mg nanoclusters produce hot electrons up to 4 eV.

Hot electrons can promote hydrogen dissociation on Mg.

Hydrogen evolution may also be facilitated by hot electrons.

Abstract

Light-driven plasmonic enhancement of chemical reactions on metal catalysts is a promising strategy to achieve highly selective and efficient chemical transformations. The study of plasmonic catalyst materials has traditionally focused on late transition metals such as Au, Ag, and Cu. In recent years, there has been increasing interest in the plasmonic properties of a set of earth-abundant elements such as Mg, which exhibit interesting hydrogenation chemistry with potential applications in hydrogen storage. This work explores the optical, electronic, and catalytic properties of a set of metallic Mg nanoclusters with up to 2057 atoms using time-dependent density functional tight-binding and density functional theory calculations. Our results show that Mg nanoclusters are able to produce highly energetic hot electrons with energies of up to 4 eV. By electronic structure analysis, we find that these hot electrons energetically align with electronic states of physisorbed molecular hydrogen, occupation of which by hot electrons can promote the hydrogen dissociation reaction. We also find that the reverse reaction, hydrogen evolution on metallic Mg, can potentially be promoted by hot electrons, but following a different mechanism. Thus, from a theoretical perspective, Mg nanoclusters display very promising behaviour for their use in light promoted storage and release of hydrogen.