Influence of the Cobalt Active Site Neighbours 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 neighbouring 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 neighbours 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. Phosphine‐assisted silane activation: The intrinsic activity of a cobalt surface site, sitting on a nickel nanoparticle, is comparatively higher when its neighbours are cobalt atoms vs. nickel atoms.