Smaller catalyst particles expose a higher step-site fraction
Supplied working report; original verdicts not validated.
Review status: Blogger published. This is an archival source note, not a passed proof.
README.md
# Smaller catalyst particles expose a higher step-site fraction **XXII, Theory 16 / Nanoscale / Catalysis** · verdict: **supported** Claim (verbatim): > Nanocatalyst selectivity is set by the ratio of step sites to terrace sites, so smaller particles are more selective for structure-sensitive reactions. ## Result The corner+edge (step) fraction of surface atoms falls from 86% at ~0.3 nm to 12% at ~5 nm. ## Headline Step sites are 86% of the surface at ~0.3 nm but only 12% at ~5 nm. ## Design Corner, edge and terrace surface atoms were counted exactly on closed-shell fcc cuboctahedra of edge length 1-20 atoms. ## Key statistics - step_fraction_small_pct = 85.7143 % - step_fraction_large_pct = 11.6942 % ## Predictions - **P1** (supported): step fraction 86% -> 12% as size grows ## Limitations - The geometric trend is exact; the link from step fraction to *selectivity* is not tested (no reaction data). - Real particles are truncated, oxidised and reconstructed, so site counts differ in detail. - A single ideal shape is assumed; the qualitative size trend holds across shapes but the numbers are shape-specific. Provenance: Closed-shell cuboctahedron site counting (van Hardeveld & Hartog magic-number clusters). *Working paper — not peer reviewed. AI-assisted. Not medical, clinical, financial or safety advice.*