Reactivity of molecular oxygen with aluminum clusters: Density functional and Ab Initio molecular dynamics simulation study

Abstract

Dissociative adsorption of molecular oxygen (O 2 ) on aluminum (Al) clusters has attracted much interest in the field of surface science and catalysis, but theoretical predictions of the reactivity of this reaction in terms of barrier height is still challenging. In this regard, we systematically investigate the reactivity of O 2 with Al clusters using density functional theory (DFT) and atom-centered density matrix propagation (ADMP) simulations. We also calculate potential energy surfaces (PESs) of the reaction between O 2 and Al clusters to estimate the barrier energy of this reaction. The M06-2X functional gives the barrier energy in agreement with the one calculated by coupled cluster singles and doubles with perturbed triples (CCSD(T)) while the TPSSh functional significantly underestimates the barrier height. The ADMP simulation using the M06-2X functional predicts the reactivity of O 2 with the Al cluster in agreement with the experimental findings, that is, singlet O 2 readily reacts with Al clusters but triplet O 2 is less reactive. We found that the ability of a DFT functional to describe the charge transfer appropriately is critical for calculating the barrier energy and the reactivity of the reaction of O 2 with Al clusters. The M06-2X functional is relevant for investigating chemical reactions involving Al and O 2 .

Density Functional Theory for Molecule–Metal Surface Reactions: When Does the Generalized Gradient Approximation Get It Right, and What to Do If It Does Not

“…The latter results led Carter and co-workers to suggest that modeling electronically nonadiabatic effects should not be necessary for O 2 + Al(111) . Specifically, electronic structure calculations based not only on ECW theory but also on hybrid DFT yield adiabatic barriers, ,− suggesting that an electronically adiabatic approach could well be valid, but that the way the electronic structure is treated is crucial. However, drawbacks of the ECW method are that it is expensive to use and that it is hard to converge the molecule–surface interaction energy with respect to the size of the embedded cluster .…”

Electronic factors determining the methane bond breaking process on small aluminum clusters

“…Whereas the interaction of oxygen with Al clusters has been studied intensively, relative few studies have been devoted to the interaction of hydrocarbons such as methane with Al clusters . This is surprising as the activation and functionalization of methane represent one of the grand challenges in modern catalysis .…”