Influence of the Cobalt Active Site Neighbors in NiCo Nanocatalysts for Phosphine‐Assisted Silane Activation

NiCo nanoparticles are active catalysts for a number of reactions, as an interesting alternative to noble metals. In particular, phosphine-covered NiCo nanoparticles with a 1:1 metal ratio were found to be active at room temperature for Si–H bond activation. However, it was unclear which of the two metals was the active site and if the neighboring atoms influenced the reaction efficiency. We designed nanoparticles with a nickel core and a limited amount of cobalt surface sites, just below or just above a monolayer amount, to investigate this question. We showed that the trend in catalytic activity is consistent with cobalt being the active site, and it shows a higher activity when its immediate neighbors are cobalt atoms. This was consistently observed with two phosphine ligands, PPh3 and PnBu3, while the first allowed a higher conversion rate than the second.