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.