Hydrogen Adsorption Mechanisms on Aluminum Clusters

Hydrogen adsorption on aluminium clusters has emerged as a focal point in the quest for efficient hydrogen storage and catalysis. Aluminium clusters, comprising anywhere from a few to several tens of atoms, display distinct electronic and geometric structures that govern their interaction with hydrogen. At small cluster sizes, quantum confinement effects lead to discrete energy levels, which can enhance adsorption at specific “magic” sizes. The adsorption process spans a continuum from weak, reversible physisorption—dominated by van der Waals forces—to strong chemisorption involving Al–H bond formation. Key factors include cluster size and shape, surface fluxionality under working conditions, support interactions, and temperature and pressure regimes. Advances in in situ spectroscopic techniques and first-principles modelling have unveiled stepwise adsorption pathways, reversible hydrogen uptake and release, and the role of dynamic cluster rearrangements. Such insights inform the design of tailored aluminium-based nanomaterials for lightweight hydrogen storage, fuel-cell catalysis and on-demand hydrogen delivery systems.

Research from Nature Portfolio

Recent studies have shown that subnanometre aluminium clusters undergo reversible hydrogen uptake via a two-stage mechanism. In one investigation, in situ synchrotron X-ray absorption spectroscopy revealed that small Al6 and Al8 clusters adsorb hydrogen initially through physisorption, followed by controlled transition to chemisorbed Al–H species upon mild heating. Another study employing first-principles molecular dynamics demonstrated that intrinsic fluxionality of aluminium clusters at room temperature exposes transient low-coordination sites, boosting hydrogen uptake by up to 25 per cent compared with static models. A further report described how tuning the electronic coupling between clusters and oxide supports allows precise adjustment of adsorption energies, enabling near-ambient hydrogen storage and release cycles with minimal energy penalty.

Hydrogen Adsorption Mechanisms on Aluminum Clusters publication trend

The graph below shows the total number of articles in hydrogen adsorption mechanisms on aluminum clusters across all publications each year (not limited to Nature Index journals).

Technical terms

Physisorption: A reversible adsorption mechanism governed by weak van der Waals forces rather than chemical bond formation.

Chemisorption: An adsorption process involving the formation of strong covalent or ionic bonds between hydrogen and the aluminium surface.

Adsorption energy: The change in energy associated with the binding of hydrogen to a cluster, indicative of adsorption strength.

Fluxionality: The dynamic rearrangement of cluster atoms that can influence adsorption sites and energies under operational conditions.

Density functional theory (DFT): A quantum mechanical modelling method used to compute electronic structure and predict adsorption behaviour.

Aluminium cluster: A finite assembly of aluminium atoms, typically comprising a few to tens of atoms, exhibiting discrete electronic states and unique reactivity compared with bulk aluminium.

References

1. Few-atom cluster model systems for a hydrogen economy. Advances in Physics X (2020).