The non-innocent role of graphene in the formation/immobilization of ultra-small gold nanoparticles functionalized with N-heterocyclic carbene ligands

Ultra-small gold nanoparticles (AuNPs) are obtained by treatment of well-defined gold complexes with reduced graphene oxide (rGO) without any auxiliary reducing agent. The AuNPs are functionalized with N-heterocyclic carbene (NHC) ligands, which allow controlling both the size and morphology, avoiding aggregation. The AuNPs are directly immobilized on the surface of graphene yielding hybrid materials composed of metal nanoparticles and a carbonaceous support. The catalytic properties of these AuNPs immobilized onto graphene have been tested in the hydration of alkynes. The AuNPs showed superior catalytic activity vs. the parent molecular gold complexes and were recycled up to ten times. We have observed that graphene plays an important role in the stabilization of AuNPs functionalized with NHC ligands