Microenvironment effect on the electronic potentials of individual (6,5)single-walled carbon nanotubes

Abstract

As one of the most fundamental properties of carbon nanotubes, the electronic states of single-walled carbon nanotubes (SWNTs) have been investigated using different experimental approaches. In this study, we report a large shift in the redox potentials and band gaps of (6,5)SWNTs with a change in the solubilizer as determined by in situ photoluminescence (PL) spectroelectrochemical measurements in both aqueous and organic solvents. This shift is attributed to the change in the microenvironment around the SWNT surfaces due to interactions between the solubilizers, including a fluorene-based copolymer (PFO-Bpy) and carboxymethyl cellulose (CMC-Na), and the SWNTs, and this behaviour was proved by molecular mechanics simulations. A striking difference was also revealed in the states of the π-electrons in the sidewalls of SWNTs solubilized in different polymers, which indicates that altering the solubilizer enables tuning of the electronic states of SWNTs. The results presented are important for understanding the effects of the microenvironment on the redox states of individual (n,m)SWNTs.