Entropy in catalyst dynamics under confinement

Qiyuan Fan

doi:10.1039/d4sc05399k

Entropy in catalyst dynamics under confinement

2024-01-01

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DOI：10.1039/d4sc05399k

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Entropy during the dynamic structural evolution of catalysts has a non-trivial influence on chemical reactions. Confinement significantly affects the catalyst dynamics and thus impacts the reactivity. However, a full understanding has not been clearly established. To investigate catalyst dynamics under confinement, we utilize the active learning scheme to effectively train machine learning potentials for computing free energies of catalytic reactions. The scheme enables us to compute the reaction free energies and entropies of O2 dissociation on Pt clusters with different sizes confined inside a carbon nanotube (CNT) at the timescale of tens of nanoseconds while keeping ab initio accuracy. We observe an entropic effect owing to liquid-to-solid phase transitions of clusters at finite temperatures. More importantly, the confinement effect enhances the structural dynamics of the cluster and leads to a lower melting temperature than those of the bare cluster and cluster outside the CNT, consequently facilitating the reaction to occur at lower temperatures and preventing the catalyst from forming unfavorable oxides. Our work reveals the important influence of confinement on structural dynamics, providing useful insight into entropy in dynamic catalysis.

Keywords:

CARBON NANOTUBES

HETEROGENEOUS CATALYSIS

METAL NANOPARTICLES

CLUSTERS

NANOCLUSTERS

IRON

Entropy in catalyst dynamics under confinement

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