Anchal Srivastava

We demonstrate a controlled growth of nitrogen-doped graphene layers by liquid precursor based chemical vapor deposition (CVD) technique. Nitrogen-doped graphene was grown directly on Cu current collectors and studied for its reversible Li-ion intercalation properties. Reversible discharge capacity of N-doped graphene is almost double compared to pristine graphene due to the large number of surface defects induced due to N-doping. All the graphene films were characterized by Raman spectroscopy, transmission electron microscopy, and X-ray photoemission spectroscopy. Direct growth of active electrode material on current collector substrates makes this a feasible and efficient process for integration into current battery manufacture technology.

With the advent of atomically thin and flat layers of conducting materials such as graphene, new designs for thin film energy storage devices with good performance have become possible. Here, we report an "in-plane" fabrication approach for ultrathin supercapacitors based on electrodes comprised of pristine graphene and multilayer reduced graphene oxide. The in-plane design is straightforward to implement and exploits efficiently the surface of each graphene layer for energy storage. The open architecture and the effect of graphene edges enable even the thinnest of devices, made from as grown 1-2 graphene layers, to reach specific capacities up to 80 μFcm(-2), while much higher (394 μFcm(-2)) specific capacities are observed multilayer reduced graphene oxide electrodes. The performances of devices with pristine as well as thicker graphene-based structures are examined using a combination of experiments and model calculations. The demonstrated all solid-state supercapacitors provide a prototype for a broad range of thin-film based energy storage devices.

Graphene has attracted a great deal of attention because of its unique band structure and electronic properties that make it promising for applications in next-generation electronic devices, transparent flexible conducting electrodes, and sensors. Here, we report the substrate selective growth of centimeter size (∼3.5 cm × 1.5 cm), uniform, and continuous single and few-layer graphene films employing chemical vapor deposition technique on polycrystalline Cu foils using liquid precursor hexane. Structural characterizations suggest that as-grown graphene films are mostly single and few layers over large areas. We have demonstrated that these graphene films can be easily transferred to any desired substrate without damage. A liquid-precursor-based synthesis route opens up a new window for simple and inexpensive growth of pristine as well as doped graphene films using various organic liquids containing the dopant atoms.