Three-dimensional amine-terminated ionic liquid functionalized graphene/Pd composite aerogel as highly efficient and recyclable catalyst for the Suzuki cross-coupling reactions

In this work, three-dimensional (3D) amine-terminated ionic liquid (IL) covalently functionalized graphene/Pd composite aerogels are successfully fabricated via a facile and green reduction-inducing self-assembly method. The morphology and composition of the obtained 3D IL-rGO/Pd composite aerogels are studied by means of TEM, SEM, XRD, FTIR, XPS, BET, and Raman spectroscopy. In those composites, the cations of NH₂-IL introduced to the surface of graphene sheets can avoid the restacking of graphene sheets and enlarge the specific surface area, which provide efficient transport pathways for improving the catalytic performance. The negatively charged Pd precursors (PdCl₄ ²⁻) are adsorbed on positively charged imidazolium ring moiety of NH₂-IL to engender Pd NPs with small particle sizes uniformly distributed on the graphene sheets, which can maximize the active surface area of catalysts and enhance their catalytic activity. The catalytic studies show that the 3D IL-rGO/Pd composite aerogels can be used as efficient, easy separation, recyclable, and stable catalysts for the Suzuki cross-coupling reactions under mild conditions, and the catalytic efficiency shows no obvious loss even after ten repeated cycles.