Metal-graphene oxide coordination network

Abstract

Three-dimensional (3-D) macroscopic graphene structures are quite attractive for various applications where large specific surface area, high porosity, low density, and outstanding electrochemical performance are needed. 3-D graphene structures have been used as energy harvester, energy storage device, stretchable electronics, sensor, cell growth scaffold, and oil absorber, showing outstanding performances compared to conventional materials and devices. Here, an ion-mediated assembly (IMA) method is developed for a substrate-initiated assembly of 3-D graphene structures. In particular, metal ions dissolved from a metal substrate by an applied voltage bring about the formation of 3-D graphene structures in the form of a coordination network of the metal and graphene oxide. Fabrication mechanism of metal-graphene oxide coordination network (MGCN) and its basic properties were investigated and discussed. The dimension and interior structure of MGCN can be precisely controlled by varying the process parameters of IMA. The ability to fabricate a 3-D graphene structure on a substrate could help open various attractive applications. In this thesis, three applications were demonstrated with the characteristic features of MGCN including selective capillarity, countless sharp edges, and expanded thermal convection. MGCN formed on a mesh was used as an oil permeable filter to separate oil and water with its selective capillarity. Countless sharp edges of MGCN were utilized to make high performance field emitter. Cylindrical and planer field emitters were fabricated by forming MGCN on metal rod and plate, respectively. MGCN formed on copper or aluminum block showed outstanding heat dissipation performance with enhanced heat transfer coefficient which comes from expanded thermal convection by MGCN.