Scaling Relations and Kinetic Monte Carlo Simulations To Bridge the Materials Gap in Heterogeneous Catalysis

Scaling relations combined with kinetic Monte Carlo simulations are used to study catalytic reactions on extended metal surfaces and nanoparticles. The reaction energies are obtained by density functional theory calculations, where the site-specific values are derived using generalized coordination numbers. This approach provides a way to handle the materials gap in heterogeneous catalysis. CO oxidation on platinum is investigated as an archetypical reaction. The kinetic simulations reveal clear differences between extended surfaces and nano particles in the size range of 1-5 nm. The presence of different types of sites on nanoparticles results in a turnover frequency that is orders of magnitude larger than on extended surfaces. For nanoparticles, the reaction conditions determine which sites dominate the overall activity. At low pressures and high temperatures, edge and corner sites determine the catalytic activity, whereas facet sites dominate the activity at high pressures and low temperatures. Furthermore, the reaction conditions are found to determine the particle-size dependence of the turnover frequency.