Two-dimensional (2D) materials have been intriguing physicists and material scientists for more than two decades due to their unique physical properties that emerge from phenomena such as charge confinement, heat flow in a 2D plane, etc. For example, graphene exhibits room temperature quantum Hall effect, quantized optical transmittance, non-local hot carrier transport, and Klein tunneling. Building on such fundamental phenomena, my work focuses on biomolecular sensing, energy generation, and storage using 2D materials such as graphene, graphene oxide, boron nitride, and 2D titanium carbide.

Chapter 1 provides an introduction to 2D materials and their current status and their applications. In Chapter 2, the effects of nitrogen dopants in graphene are investigated for its possible applications as a selective permeable membrane. Specifically, I investigated theoretically and confirmed experimentally the influence of nitrogen dopant configuration (viz., graphitic, pyridinic, and pyrrolic) on selective gas permeability of graphene. The N-dopants in non-graphitic configurations (pyridinic and pyrrolic) showed selective permeability to O2 unlike graphitic N-dopants. These results implied that N-doped graphene could potentially be used as an O2 selective permeable membrane in devices such as Li-air batteries. In addition to the use of high surface area 2D materials in energy storage as discussed in Chapter 2, I also demonstrated the use of 2D materials (particularly, graphene and titanium carbide) for energy generation as described in Chapter 3 using novel "triboelectric nanogenerators (TENGs)". Notably, in Chapter 3 I provide blueprints for flexible and wearable TENGs that can be directly integrated with textiles, automobiles, and ocean wave energy harvesters. Lastly, in Chapter 3 I demonstrate new strategies for additive manufacturing of 2D material-based TENGs that convert mechanical energy into electricity and wirelessly transmit it for storage in batteries and capacitors. In Chapter 4, the use of novel 2D nanomaterials such as graphene, graphene oxide, and boron nitride for bio-sensing applications is demonstrated. In particular, the fundamental interactions of aromatic amino acids viz., tyrosine, tryptophan, and phenylalanine with 2D materials were studied using a comprehensive array of tools including Raman spectroscopy, cyclic voltammetry, and photoluminescence spectroscopy.

In summary, my work epitomizes the unique electronic and optical properties of 2D materials and their use in a variety of sensors and sustainable energy devices.