Towards 3D Architectures Composed of 2D Materials

A. Garcia


Two-dimensional (2D) materials such as graphene have been a topic of intense study as these atomically thin materials have shown enhanced characteristics ideal for applications such as renewable energy storage and electrochemical sensing, which has led researchers into a frenzy akin to that of prospectors during the gold rush. While there still is gold to be found, there is also fool’s gold when systematic studies are not performed. In order to develop new processes for fabricating 3D high surface area architectures, we investigated mechanisms at a fundamental level throughout this work. It is known that the surfaces of freestanding 2D graphene sheets exhibits record-breaking electrical and thermal conductivity, remarkable chemical stability, mechanical strength, and naturally high specific surface area, however, current 2D techniques lay the graphene sheets onto substrates, typically decreasing electron transport and always reducing accessible surface area. In order to use sides of a graphene sheet for applications that require high surface area, we took inspiration from origami. A single paper cannot support itself, but when it becomes part of a 3-dimensional (3D) structure, support becomes natural. The first phase of my work involved the use of minimal surface inspired 3D nickel templates to create free-standing graphene structures with inherited morphology, resulting in porous well-defined sponge-like structures of free-standing graphene. The concept of graphene shaped into minimal surfaces architectures is of great interest; theories predict unique mechanical properties, such as a young’s modulus of 1 TPa for single crystal graphene and an exceptionally high stiffness for minimal surface architectures. Few studies have been performed of fabricating graphene architectures with well defined pore sizes, co-continuous pores, and controlled layer thickness needed for enhancing mass transport and electronic conductivity. Studies were also performed involving atomistic control of impurities of these 3D graphene-based structures to effect electronic structure and chemical properties of graphene, creating a tunable range of characteristics for this multifunctional material. 3D graphene in minimal surface architectures shows potential for enhancing the capabilities of standard carbon-based applications and creating niche applications, but only when key challenges of controlling architecture and graphene quality are addressed