Composites of Graphene Quantum Dots and Reduced Graphene\nOxide as Catalysts for Nitroarene Reduction

Abstract

Composites of graphene\nquantum dots (GQDs) and reduced graphene\noxide (rGO) with unique three-dimensional (3D) structure are prepared\nand their catalytic activities for reduction of nitroarenes are explored.\nWe demonstrate that the 3D GQDs/rGO composites are more active in\nnitroarene reduction than GQDs and rGO. Some of them are even more\nactive than the Ag-embedded calcium alginate (Ag/CA) or Au-embedded\ncalcium alginate (Au/CA) catalysts. Interestingly, their catalytic\nproperty is closely related to the ratio of GQDs to rGO in the 3D\nGQDs/rGO composites and GQDs-to-rGO mass ratio of 1/4 exhibits the\nhighest catalytic activity. Raman spectra of the composites show that\nGQDs-to-rGO ratio is related to the number of the surface/edge defects,\nindicating that the sites of defect and edges are active sites. In\naddition, the catalytic performance of the 3D GQDs/rGO composites\nis also contributed by their unique 3D network structures that are\nbeneficial for the reactant adsorption and product diffusion. Given\nalso the long cycling duration and the easy recovery from the reaction\nsystem, 3D GQDs/rGO composites are potential applicable metal-free\ncatalytic system for nitorarene reduction.