Isotropic and Oriented Copper Nanoparticles Supported on Graphene as Aniline Guanylation Catalysts

Abstract

Adsorption of copper nanoparticles (NPs) on preformed graphene (G) affords an efficient catalyst for the nucleophilic addition of anilines to N,N'-dialkylcarbodiimides to form the corresponding guanidines. Cu/G exhibits a wide scope in promoting guanylation of different substituted anilines and carbodiimides and outperforms Cu nanoparticles supported on carbon nanotubes, active carbon, layered clay, TiO2 and CeO2. Importantly, the performance of the catalyst could be increased by 3 orders of magnitude, reaching TONs of 5.95 x 10(4) and TOFs of 9.9 x 10(2) h(-1) by using as catalysts films of 1.1.1 facet oriented Cu nanoplatelets (3-4 nm thickness and 20-40 nm lateral dimensions) having a strong interaction with G. This enhancement of the catalytic activity derives from the preferential facet orientation of Cu nano platelets and their strong grafting on G. These catalytic results show the potential that G offers as support for metal NPs for the development of highly active recoverable heterogeneous catalysts.