Nanoparticle Active-Site Reactivity

Nanoparticle

Particle radius 2.3

Temperature 450 K

Structure sensitivity 1.5

Coordination sites

Corner

Edge

Terrace

Bulk

Turnover

Total atoms

–

Dispersion

–

TOF (rxn/s)

–

Total reacted

–

How it works

Each atom's position comes from a real FCC lattice cluster. Counting how many lattice neighbors sit within bonding distance gives its coordination number (CN): 12 deep inside the bulk, 9 on a flat terrace facet, 7 along an edge, and 6 or fewer at a corner or vertex. Undercoordinated atoms have dangling bonds, which the model turns directly into a lower activation barrier — the same generalized-coordination-number trend used to rank real nanoparticle catalysts.

Ea(CN) = Ea0 − sensitivity·(12−CN)·ΔE
k(site) = exp(−Ea(CN) / (kB·T))

Particle radius — bigger particles have more bulk-like terrace atoms and a smaller fraction of corners/edges (lower dispersion), mirroring why nanocatalysts lose specific activity as they grow or sinter.
Temperature — raises every site's Arrhenius rate constant, but low-barrier corner sites benefit least (they are already near barrierless) while high-barrier terrace sites gain the most.
Structure sensitivity — 0 makes every site equally reactive (a "structure-insensitive" reaction); high values make only corners and edges react at all, the hallmark of a strongly structure-sensitive reaction.
Gas molecules drift toward the cluster and attempt a reaction on contact with the nearest surface atom; a flash marks a successful turnover, and the site briefly lights up. Failed collisions simply bounce off, exactly as most real gas-surface collisions do.

Corner (CN≤6) Edge (CN 7–8) Terrace (CN 9–10) Bulk (CN≥11) Gas molecule

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