Organometallic Functionalization of 2D Nanomaterials for Energy and Medical Applications

This dissertation focuses on the development and understanding of organometallic, ring-centered functionalization strategies for two-dimensional nanomaterials, with particular emphasis on graphene and hexagonal boron nitride (h-BN). The central theme of this work is the use of coordination-based chemistry to engineer nanoscale interfaces while preserving lattice planarity and charge transport properties that are critical for electronic and diagnostic applications. Unlike conventional covalent modification routes that disrupt sp² hybridization and degrade electronic performance, the approaches explored here rely on organometallic interactions with delocalized π-systems to achieve controlled functionalization with minimal structural damage. The primary objectives of this dissertation were: (1) to investigate the feasibility and mechanism of ring-centered organometallic functionalization on both conductive and insulating two-dimensional materials; (2) to evaluate the impact of such functionalization on structural integrity, vibrational signatures, and carrier transport properties; and (3) to demonstrate how engineered graphene interfaces can be leveraged in both nanoelectronic devices and exploratory biomedical diagnostic platforms. To accomplish these objectives, a wide range of synthesis, fabrication, and characterization techniques were employed, including chemical vapor deposition (CVD), vapor-phase organometallic reactions, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and electrical transport measurements using back-gated graphene field-effect transistor (FET) devices fabricated through photolithography and thin-film processing. A major contribution of this work is the development of ring-centered η⁶ organometallic functionalization of hexagonal boron nitride, a chemically inert and wide-band-gap two-dimensional insulator. While h-BN is widely used as a dielectric substrate for graphene electronics, its lack of reactivity has limited its use as an active interface. In this dissertation, η⁶ coordination chemistry is shown to provide a viable pathway for functionalizing the basal plane of h-BN without relying on defects or edges. Structural and spectroscopic analysis indicates that, unlike graphene, the polar nature of B–N bonds leads to asymmetric metal coordination and slight lattice puckering following functionalization. These findings establish fundamental differences between graphene and h-BN under ring-centered organometallic chemistry and provide new insight into interface engineering for insulating two-dimensional materials. This dissertation further demonstrates a vapor-phase hafnium functionalization strategy for graphene aimed at enabling high-mobility nanoelectronic applications. Hafnium-based organometallic precursors were introduced under controlled vapor-phase conditions to modify graphene without introducing extensive lattice disorder. Raman spectroscopy and electrical transport measurements reveal that, despite chemical modification, the sp² framework of graphene is largely preserved and carrier mobility is enhanced or retained relative to unfunctionalized control devices. These results highlight the potential of carefully designed organometallic chemistry to improve graphene–dielectric and graphene–contact interfaces, offering an alternative to conventional surface treatments that often compromise device performance. In addition to electronic applications, this work explores graphene as an interfacial transducer for biological systems, focusing on its interaction with human skin tissue samples associated with basal cell carcinoma and squamous cell carcinoma. By monitoring changes in graphene’s Raman spectral features upon contact with different tissue types, this study evaluates the feasibility of using graphene as a nano-diagnostic platform. While shifts in Raman features were observed, the results exhibit significant variability and overlap between normal and cancerous tissues. Rather than presenting definitive diagnostic separation, this work emphasizes the importance of recognizing ambiguity arising from biological heterogeneity, interfacial strain, and competing doping mechanisms. These findings provide a realistic assessment of the limitations of graphene-based Raman diagnostics and underscore the need for cautious interpretation in translational biomedical applications. Overall, this dissertation establishes organometallic, ring-centered functionalization as a versatile and physically grounded strategy for modifying two-dimensional materials. By spanning fundamental coordination chemistry, nanoelectronic device performance, and exploratory biomedical diagnostics, this work demonstrates how interface engineering at the atomic scale can enable multifunctional platforms while also revealing intrinsic limitations that must be addressed for future technological deployment.

Author dc:creator

• Kartikey Sharma (12486409)

• Engineering
• Chemical

Statement dc:rights

• In Copyright

DOI dc:identifier

https://doi.org/10.25417/uic.32993999.v1

OAI identifier oai:identifier

oai:figshare.com:article/32993999