Fabrication and catalytic performance of a new diaminopyridine Pd(II) monolayer supported on graphene oxide for catalyzing Suzuki coupling reaction

Abstract

A new “Chanel like” diaminopyridine Pd(II) catalytic monolayer supported on Graphene Oxide (called GO@DAP-Pd) was prepared by self-assembly (SA) and characterized by XRD, Raman, FT-IR, SEM, TEM and XPS. Catalytic property of GO@DAP-Pd prepared use different Pd source in Suzuki coupling reaction was explored, in which the catalytic activity can be influenced with different palladium sources due to the different size of Pd nanoparticles formed. GO@DAP-Pd1 fabricated with (C6H5CN)2PdCl2 as Pd source, exhibited a higher catalytic activity and could be reused at least 7 times. The deactivation of catalyst was mainly due to the aggregation of active Pd and the loss of a small amount of active Pd, resulting in the deactivation of the catalyst. The catalytic mechanism was detail explored by hot filtration, poisoning experiments, XRD, Raman, XPS and React IR, and the results showed that catalytic process occurred at the interface, including substrates adsorption, intermediate formation and product desorption. The structure and synergy in active sites containing PdO(110), Pd(200, 111) and Pd(111)/PdO(002) are crucial to enhance the catalytic activity. The method to form the multi-active sites in situ on the surface of organometallic monolayer can supply an efficient way to design and prepare the high active catalytic monolayer.