Chemistry of Graphene Nanoribbons

Abstract

This cumulative dissertation presents two main topics: 1. The oxidative unzipping of monodisperse single-walled carbon nanotubes (SWCNTs) to fabricate oxo-graphene nanoribbons (oxo-GNRs) with uniformwidths. 2. The orthogonal functionalization of those ribbons on edges and the basal plane. Graphene nanoribbons (GNRs) are narrow quasi-one-dimensional graphene strips that exhibit highly tunable electronic properties determined by their width, edge configuration, and functionalization. The chemical unzipping of carbon nanotubes offers a promising approach for producing GNRs at scales necessary for industrial applications like nanoelectronics. The primary objective of this work is to establish a reliable method for synthesizing oxo-GNRs by oxidatively unzipping SWCNTs using a mild oxidation protocol adapted fromEigler and coworkers’ oxo-graphene synthesis with potassium permanganate and sulfuric acid. EmployingSWCNTs with uniformchirality, like (6,5)-CNTs, ensures the fabrication of nanoribbons with consistent widths - an essential feature for potential applications. A focus of this work is the comprehensive characterization of oxo-GNRs, including their chemical composition, morphology, and optical properties. Key findings, including the discovery of photoluminescence of oxo-GNRs and the precise identification and localization of oxo-groups, are substantiated through comprehensive experimental data and chemical derivatization. This research addresses a gap of knowledge by developing a robust structural model to link synthesis parameters with the resulting nanoribbon properties, thereby overcoming limitations in understanding structure-property relationships. The second part of this work develops an orthogonal functionalization strategy for selectively modifying the edges and π-surface of oxo-GNRs. This is achieved through reactions with phenylhydrazine derivatives and diazonium chemistry, enabling precise control over the placement of the resulting groups on the edges or basal plane of the ribbons, respectively. The findings of this study advance scalable GNR synthesis and targeted functionalization of oxidized graphene materials and contribute to the understanding of their structural and chemical properties. Future research may focus on expanding functionalization strategies and integrating GNRs into nanoelectronic devices to explore their electronic properties.