A Comprehensive Overview of Active Sites of fcc-Co Nanoparticles and Their Role in CO Splitting─A DFT Study

When modeling catalytically active sites in fcc metal nanoparticles (NPs), most theoretical studies often rely on just a handful of low-index surfaces, which might lead to overlooking surface sites that are important in the reaction. In this work, we identify 13 distinct types of low-coordinated sites (LCS) on fcc-Co catalysts and keep track of their concentration evolution with particle size. By calculating CO dissociation barriers, we show that these sites are characterized by significantly different reactivities and discover active sites with lower barriers than previously known. In addition, we classify the most active sites of small Co nanoparticles that are typically not modeled. More generally, this work provides guidance in choosing relevant surface models based on particle sizes.