Dynamic evolution of specific catalytic sites on Pt nanoparticles

Abstract

Platinum nanoparticles are widely used catalysts in many important industrial applications, in the chemical, petrochemical, automotive and energy sectors. Due to the extremely high cost and the limited abundance of platinum, improving the efficiency of platinum-based nanocatalysts is key to the economic development of these materials, as well as being a challenge for basic research. Ultimately we seek to increase the active surfaces area, per unit volume, and to preserve the activity and selectivity over the functional lifetime of the product. In this work the formation of platinum nanoparticles is investigated by molecular dynamic simulations under different conditions of temperature and atomic deposition rates to identify the conditions that give rise to a greater density of different types of surface active sites. By tuning the growth conditions we obtained highly non-equilibrium morphologies with branches that expose larger surface areas that are consistent with experimental observations. The results are also used to clarify the relationship between growth conditions, surface structure and catalytic functionality based on a simple surface defect classification model, which differentiates between CO oxidation reactions, hydrogen evolution reactions (HER) and hydrogen oxidation reactions (HOR).