Metal nanoparticles supported graphene oxide 3D porous monoliths and their excellent catalytic activity

Graphene oxide (GO) and reduced graphene oxide (RGO) 3D porous monoliths were prepared using a simple and green method, unidirectional freeze-drying method. Gold or silver nanoparticles were deposited on the GO nanosheets to form Au/GO and Ag/GO nanocomposites under the reducing action of GO without using any reducing agent or surfactant. The Au or Ag nanoparticles loaded GO 3D porous monoliths (Au/GO or Ag/GO 3D porous monoliths) prepared from Au/GO and Ag/GO nanocomposites by unidirectional freeze-drying method had an order (unidirectional) porous structure and high porosity. The Au/GO or Au/RGO 3D porous monoliths not only had high catalytic activity in the reduction of 4-nitrophenol and Suzuki–Miyaura coupling reaction, but also showed good recyclability.