Topic: 3D interconnected graphene foams and 1D graphene nanoribbons by CVD
Speaker: Prof.Zongping Chen, Max Planck Institute for Polymer Research
Time: 9:00, May 4, 2017
Venue: Room 205, Building 14, Wushan Campus
Abstract:
Graphene is a two-dimensional monolayer of carbon atoms packed into a honeycomb lattice that possesses a wealth of new physics and fascinating electrical, thermal, and mechanical properties. To harness these properties for macroscopic applications, both large-scale synthesis and integration of high-quality individual graphene sheets to advanced multi-functional structures are required. Here chemical vapor deposition (CVD) synthesis of high-quality graphene three-dimensional (3D) network structure, which we named graphene foams (GFs), was systematically studied. The graphene sheets in the GFs are seamlessly interconnected into a 3D flexible network as the fast transport channel of charge carriers. The GFs show a high electrical conductivity, an ultra-low density, a high porosity and a very high specific surface area, which shows great potential for many applications, such as highly-conductive composites and elastic conductors, lightweight high-performance electromagnetic interference shielding materials, flexible lithium ion battery with ultrafast charge and discharge rates, and highly-sensitive gas sensors.
However, graphene is a two-dimensional semi-metallic crystal with zero bandgap, which hindes its use in many electronic and optoelectronic devices. Graphene nanoribbons (GNRs), quasi-one-dimensional narrow strips of graphene, have shown great promise for use as advanced semiconductors in electronics. An efficient CVD process was also demonstrated for inexpensive and high-throughput growth of structurally defined GNRs over large areas. The CVD-grown GNRs exhibit similar structures and properties with those synthesized under UHV conditions. Homogenous GNR films over areas of centimetres have been successfully transferred to non-conducting wafers and exhibited a large current on/off ratio in field-effect transistor devices, This “bottom-up” CVD method further allows the growth of other kinds of sturctures, demonstrating the versatility and scalability of this process, which provides access to a broad class of GNRs with engineered structures and properties based on molecular-scale design. These results pave the way toward the scalable and controllable growth of GNRs, and provide practical solutions to the current challenges in graphene-based nanoelectronic, optoelectronic and photonic devices.