Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2014)

New techniques for rapid graphite oxide reduction are illustrated. By exposing graphite oxide to a high intensity light, such as a camera flash, rapid deflagration and deoxygenation takes place. The resulting graphitic material is a conductor, with two orders of magnitude higher surface area than its insulating precursor. The technique has potential applications in micro patterning as well as distributed ignition. Flashed graphite oxide is also dispersable in a variety of organic solvents, making it compatible with polymer processing. Another synthetic route to graphene is through solvothermal reduction of graphite oxide. Refluxing dispersions of graphite oxide in N-Methyl-2-pyrrolidone yields charge stabilized colloidal dispersions of graphene. The mechanism of reduction is thermal in nature, while charge stabilization is accomplished through functionalization of graphene NMP moieties and surface energy matching of NMP to graphene sheets.

Conductometric graphene/Pd(0) hydrogen sensors with increased sensitivity compared to pure graphene is demonstrated. Pd(0) nanoparticles on graphene's surface lower the adsorption energy barrier for H2 molecules and improve the surface chemisorption of H2.

An inexpensive, solid-state method for producing graphene based electronic materials is presented. Utilizing an inexpensive LightScribe DVD drive to reduce graphene oxide to graphene, patterning any design on a variety of substrates is demonstrated. Highly reduced laser scribed graphene shows promise in applications such as supercapacitors, sensors and electrocatalysts. Metal nanoparticles can be grown directly on the graphene surfaces using metal salt precursors. Light initiated reactions enable formation of nanoparticles within seconds of laser exposure. Such a universal approach to nanoparticle formation is suitable for applications from supercapacitors to catalysis.

An investigation into barrier properties of graphene and graphene oxide films illustrate excellent barrier characteristics of graphene oxide to all gases at STP conditions with rates of permeability being directly related to the kinetic diameter of the gas. Due to the hydrophilic nature of graphene oxide, it is highly susceptible to permeation of water through its layered structure. Barrier properties of graphene to water illustrate at least 60 times lower rates of permeability per unit of thickness.

    Cover page: Synthetic Routes to Graphene for Applications in Barrier Materials and Energy Storage
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2014)
    The integration of multiple synergistic catalytic systems can enable the creation of biocompatible enzymatic mimics for cascading reactions under physiologically relevant conditions. Here we report the design of a graphene-haemin-glucose oxidase conjugate as a tandem catalyst, in which graphene functions as a unique support to integrate molecular catalyst haemin and enzymatic catalyst glucose oxidase for biomimetic generation of antithrombotic species. Monomeric haemin can be conjugated with graphene through π-π interactions to function as an effective catalyst for the oxidation of endogenous L-arginine by hydrogen peroxide. Furthermore, glucose oxidase can be covalently linked onto graphene for local generation of hydrogen peroxide through the oxidation of blood glucose. Thus, the integrated graphene-haemin-glucose oxidase catalysts can readily enable the continuous generation of nitroxyl, an antithrombotic species, from physiologically abundant glucose and L-arginine. Finally, we demonstrate that the conjugates can be embedded within polyurethane to create a long-lasting antithrombotic coating for blood-contacting biomedical devices.
      Cover page: Integration of molecular and enzymatic catalysts on graphene for biomimetic generation of antithrombotic species
      Top