Size effect in thiol and amine binding to small Pt nanoparticles

A study was carried out to compare the binding affinities of 1-dodecanethiol and dodecylamine for small Pt nanoparticles. The results showed that the affinity of thiol for Pt nanoparticles increases with increasing particle size whereas the affinity of amine for Pt nanoparticles decreases. The divergence in binding affinities has resulted in differences in catalytic activities of thiol- and amine-protected Pt nanoparticles in the room temperature electro-oxidation of methanol (a fuel cell reaction). It was therefore possible for the larger Pt nanoparticles to be catalytically more active than the smaller Pt nanoparticles up to a certain critical size, before the surface area effects of nanoparticles become noticeable.