Functionalized Graphene Based Sensors for Nitric Oxide Detection

Abstract

Nitric oxide (NO) is a small and reactive biomolecule involved in a variety of physiological processes including the vasodilation, immune, and nervous systems. Sensing of NO is important in order to elucidate the biological pathways in which NO participates. There is interest in developing NO sensors from carbon-based materials in order to decrease the price of sensors from transition metal-based electrodes, as well as offer improved sensing performance over existing sensors. In this thesis, electrodes based on functionalized grapheme sheets (FGSs) are investigated for performance as electrochemical NO sensors. First, multiple methods of generating NO were studied in order to gain understanding and control of experimental conditions. It was determined that the most reliable means of NO production is from bubbling the gas itself. Monolayer electrodes were made using FGS materials with different chemical properties, and the effect of FGS structure and composition was correlated to intrinsic NO sensing performance. These electrodes were compared to the performance of a platinized Pt electrode as the baseline. Porous electrodes made from FGSs were also made to examine the relative effects of intrinsic and morphological properties. Sensing performance was evaluated using cyclic voltammetry, and electrodes were characterized using scanning electron microsopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and porosity simulations. It was demonstrated that the FGS materials with more lattice defect sites were more catalytic toward NO oxidation. A moderate amount of porosity was shown to improve the performance of the FGS electrodes.