Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Computational Insights into Selectivity of Emissive Defect via Nanotube-Catalyzed Fenton Reaction

An aqueous nanotube-catalyzed Fenton reaction with 150 diverse molecules — alcohols, amines, carbonyls, acrylates, amino acids, and peptides — has been shown to create emissive sp³ defects on single-walled carbon nanotubes (SWCNTs), introduced in selected configurations allowing emission at specific wavelengths. While such selectivity is technologically important, the underlying reaction mechanisms remain poorly understood. Using density functional theory, we investigate 17 representative molecules bound to a (6,5) SWCNT at six defect configurations (three ortho and three para). The emission energies for ortho (O87) and para (P87) defects oriented at 87° relative to the nanotube axis reproduce experimental peaks (1150 and 1250 nm), while changes in adducts cause minor shifts (10–15 meV). However, experimental spectra depend strongly on the specific adduct: ethanol produces only 1250 nm peak, while 1-propanol produces both 1150 nm and 1250 nm peaks. Our calculations attribute this to the activation of different reactive sites, resulting on P₈₇, O₈₇, or both defects, depending on the adduct. Further analysis shows that the preference for a specific defect is governed by the structural and electronic properties of the nanotube–adduct intermediate, including s-character, partial charge, and π-orbital misalignment. The correlations between these parameters establish mechanisms for selective defect formation either via a radical or charge-mediated attachment, providing an explanation for tunable emission in functionalized SWCNTs via Fenton reaction.