%0 Generic
%9 Doctoral Dissertation
%A Wang, Yan
%D 2020
%F pittir:38458
%K Sustainable Material Design, Surface Chemistry, Fuel Cell, Antioxidant Deactivation, Antimicrobial Activity, Density Functional Theory
%T Toward Rational Design of Graphene Nanomaterials: Manipulating Chemical Composition to Identify Governing Properties for Electrochemical and Biological Activities
%U http://d-scholarship-dev.library.pitt.edu/38458/
%X The unique properties of graphene-based nanomaterials (GMs) have enabled various applications in the fields of electronics, energy, environment, and biotechnology. Yet, their potential inherent hazard poses risks to human health and the environment, which could be a barrier to the success of these applications. A critical underpinning of sustainable material development is rational design. This approach involves the ability to control material outcomes, requiring the establishment of property-function and property-hazard relationships. This dissertation aims to demonstrate an ability to rationally design GMs by manipulating chemical composition and establishing the relationships that correlate material properties to their electrochemical activity (function) and bioactivity (hazard). The electrochemical activity is represented by the material reactivity for important electrochemical reactions (oxygen reduction reaction, ORR and oxygen evolution reaction, OER). The bioactivity is represented as the material propensity to oxidize a cellular biomolecule (glutathione) and inactivate the bacteria (Escherichia coli).    Material sets of graphene oxide (GO) and nitrogen-doped graphene (NG) are investigated using various complementary characterization techniques to determine the material properties that govern electrochemical and biological activities as chemical composition changes. The results suggest both activities are governed by synergistic effects from multiple properties, including specific oxygen and nitrogen sites and properties arising as a consequence of changing chemical composition. Enhanced aqueous dispersion and defect density are important for GO bioactivity. Additionally, coupled experimental and computational approaches elucidate the synergistic role of adjacent epoxide and hydroxyl groups on GO in directly oxidizing glutathione. As the surface of GO is reduced, the electrochemical and biological activities are governed by a balance of carbonyl groups and electrical conductivity. For NG, N-types control electrochemical reactions, ORR (graphitic-N) and OER (pyridinic-N). Further, the predominance of graphitic-N enhances oxidative stress-related bioactivity, which is an important contribution since very little is known surrounding NG bioactivity.    Collectively, this dissertation supports the use of chemical composition manipulation to control material properties and in turn, function and hazard outcomes. The established property-function and property-hazard relationships provide rational design guidance for GMs. The holistic approach herein is applicable to other nanomaterials and thus, will continue to contribute to the advancement of sustainable nanotechnology.