Pd-Cu alloy nanoparticle supported on amine-terminated ionic liquid functional 3D graphene and its application on Suzuki cross-coupling reaction

Well distributed Pd-Cu bimetallic alloy nanoparticles supported on amine-terminated ionic liquid functional three-dimensional graphene (3D IL-rGO/Pd-Cu) as an efficient catalyst for Suzuki cross-coupling reaction has been prepared via a facile synthetic method. The introduction of IL-NH₂ cations on the surface of graphene sheets can effectively avoid the re-deposition of graphene sheets, allowing the catalyst to be reused up to 10 cycles. The addition of Cu not only saves cost but also ensures high catalytic efficiency. It is worthy to note that the catalyst 3D IL-rGO/Pd_2.5Cu_2.5 can efficiently catalyze the Suzuki cross-coupling reaction with the yield up to 100% in 0.25 h, almost one-fold higher than that by the pristine IL-rGO/Pd_2.5 catalyst (52%). The Powder X-Ray Diffraction (XRD), combining energy dispersive X-ray spectroscopy (EDS) mapping results confirm the existence and distribution of Pd and Cu in the bimetallic nanoparticles. The transmission electron microscopy (TEM) reveals the nanoparticle size with an average diameter of 3.0 ± 0.5 nm. X-ray photoelectron spectroscopy (XPS) analysis proved the presence of electron transfer from Cu to Pd upon alloying. Such alloying-induced electronic modification of Pd-Cu alloy and 3D ionic liquid functional graphene with large specific surface area both accounted for the catalytic enhancement.