Effect of solvent, pH and thermal annealing on carbon nanotube functionalization
Year: 2026
Type: preprint
Abstract: Quantum well defect-modified single-walled carbon nanotubes are environmentally responsive nanomaterials with broad potential in biosensing, imaging, and quantum computing. The most widely used approach for their covalent functionalization relies on aryl diazonium chemistry, which introduces sp 3 -hybridized aryl defect sites onto the nanotube lattice. Here we investigate how solvent, pH, substituent electronics, and thermal annealing influence the functionalization of SWCNTs with aryl diazonium salts. This approach involves ‘over-functionalization’ with aryl groups resulting in loss of optical properties, followed by thermal annealing to reduce defect density. We find that solvent choice changes both the Raman D:G ratio and the relative intensity of E 11 , E 11 -, and, in some cases, E 11 *- emission. Thermal annealing at 200 °C under ambient atmosphere typically restores fluorescence from initially quenched samples, consistent with partial recovery from an overfunctionalized state. Finally, pH-dependent experiments suggest that electron-poor NO 2 PhN 2 -BF 4 reacts most effectively under acidic conditions, whereas electron-rich OMePhN 2 -BF 4 is more strongly activated under basic conditions. Overall, solvent and pH control the degree and optical outcome of aryl diazonium functionalization, while thermal annealing provides a practical post-reaction route for recovering useful defect emission from over-functionalized nanotubes. To our knowledge, this work provides the first systematic analysis of how solvent and pH govern quantum-well defect formation in aryl-functionalized SWCNTs.
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7161765761