11/13/2025
By Kwok Fan Chow

The Kennedy College of Science, Department of Chemistry, invites you to attend a Ph.D. Research Proposal defense by Jia Tu entitled “Substrate-Modulated Reactivity of Pristine Graphene.”

Date: Thursday, November 20, 2025
Time: 10 a.m. – noon
Location: Olney Hall 518

Committee:

  • Chair: Prof. Mingdi Yan, Department of Chemistry, University of Massachusetts Lowell
  • Prof. Olof Ramström, Department of Chemistry, University of Massachusetts Lowell
  • Prof. Lawrence Wolf, Department of Chemistry, University of Massachusetts Lowell
  • Prof. Michael Ross, Department of Chemistry, University of Massachusetts Lowell

Abstract:

The chemical reactivity of pristine graphene is profoundly influenced by its interaction with the supporting substrate through charge transfer, and strain. This dissertation investigates how the morphology and crystallographic orientation of metal substrates—particularly Cu(111)—modulate graphene’s electronic structure and chemical reactivity, providing a mechanistic foundation for the controlled covalent functionalization of graphene.

In the first part of this work, a strain-free abnormal grain growth strategy was developed to fabricate centimeter-scale single-crystal Cu(111) foils from commercial polycrystalline copper under optimized conditions (1060 °C, 3 h). The process was integrated into a home-built CVD system, enabling the direct growth of high-quality monolayer graphene on Cu(111). Molecular dynamics simulations confirmed that strain-free annealing facilitates the migration and coalescence of Cu grains into large Cu(111) domains. The resulting graphene exhibited minimal defects, and high uniformity, establishing an ideal platform for studying substrate-modulated reactivity

Building on this platform, the inverse-electron-demand Diels–Alder (IEDDA) reaction between tropone and graphene supported on Cu(111) was explored under Lewis acid catalysis. The reaction revealed a striking catalyst-dependent selectivity, where B(C₆F₅)₃ promoted a [4 + 2] cycloaddition yielding carbonyl-functionalized graphene, while BPh₃ favored an [8 + 2] pathway forming C–O linkages. Raman and XPS analyses confirmed the formation of oxygen-containing functional groups, and DFT calculations elucidated that the Lewis acid dissociation energy dictates the reaction pathway. The Cu(111) substrate enhanced reactivity by introducing n-type doping, activating graphene as an electron-rich dienophile. This study establishes a dual activation mechanism combining substrate and catalyst effects, opening a new route for selective covalent modification of pristine graphene

Finally, the substrate-dependent nitrene cycloaddition of graphene with perfluorophenyl azides (PFPA) was systematically investigated to probe how lattice orientation and surface morphology control reactivity. Raman spectrum revealed that graphene supported on Cu(111) exhibited the highest extent of functionalization, while graphene on polycrystalline Cu or SiO₂/Si showed significantly lower reactivity. This enhancement is attributed to stronger substrate–graphene interaction, charge transfer, and strain-induced orbital distortion, which collectively lower the activation barrier for nitrene addition. The study establishes substrate morphology and crystallography as tunable parameters for directing graphene’s covalent chemistry.

Collectively, this dissertation integrates synthesis, spectroscopy, and computation to uncover how substrate engineering governs graphene’s chemical reactivity. The findings provide fundamental insights for designing substrate-controlled functionalization strategies and advance the development of chemically tunable 2D materials for applications in nanoelectronics, sensing, and catalysis.

All interested students and faculty members are invited to attend.