Note that the facile surface diffusion of most intermediate species does not imply the negligible effect of the distinction between catalytic activities of edge and terrace sites on the reaction kinetics. Indeed, edges and other low-coordination sites are far less common than (111) facets on the catalyst surface, and their surface concentration diminishes as the catalyst nanoparticle size grows. Consequently, key reaction steps at these sparse sites could bottleneck catalytic activity unless addressed in catalyst design.