General acid and base bifunctional graphene oxide for cooperative catalysis

Abstract

In this study, a bifunctional graphene oxide material (GO–AEP–UDP) with a general acid, the ureidopropyl (UDP) group, and a general base, the 3-[2-(2-aminoethylamino)ethylamino]-propyl (AEP) group, was synthesized by silylanization of graphene oxide (GO) with organoalkoxysilane precursors. Characterization of the obtained GO–AEP–UDP was carried out by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. Systematic studies demonstrated that GO–AEP–UDP has superior catalytic performance in the classic Henry reaction of 4-nitrobenzaldehyde with nitromethane. It was found that the relative concentration and spatial arrangement of cooperative functional groups were very important factors in the synergistic catalysis.