Size and structure effects on platinum nanocatalysts: theoretical insights from methanol dehydrogenation

Methanol dehydrogenation on Pt nanoparticles was studied as a model reaction with the focus on size and structure effects employing the density functional theory approach. The effect of cluster morphology is manifested by the higher adsorption energy of COH_x intermediates on vertexes and edges of model nanoparticles compared to closely packed terraces. Moreover, due to the size effect, the adsorption sites of Pt₇₉ nanoparticles (1.2 nm in diameter) exhibit considerably higher adsorption activity than the same sites of Pt₂₀₁ (1.7 nm). Thus, particles with a size of about 1 nm are shown to be more active due to the superposition of two effects: (i) a higher surface fraction of low-coordinated adsorption sites and (ii) higher activity of these sites compared to particles with a size of about 2 nm.