Size-dependent catalytic activation energy of Pt nanocrystals

Abstract

Based on a size-dependent melting model, we present a thermodynamic expression to describe the catalytic activation energy E_a(D)/E_a of Pt nanocrystals. As the size drops, the E_a(D)/E_a curves gradually decrease, which is consistent with the prediction of our model and other theoretical models and experimental results. In addition, we find that E_a(D)/E_a is correlated with the root mean square displacement ratio of the surface atoms to the atoms in the nanocrystals σ_s(D)(Che and Bennett, n.d.²⁾/σ_v(D)(Che and Bennett, n.d.²⁾, and the smaller the size, the greater the correlation. For nanocrystals of different dimensions, we find that the E_a(D)/E_a nanoparticles exhibit the strongest size dependence, followed by nanowires, and that of thin film is the weakest.