Using cyclic voltammetry to measure bandgap modulation of functionalized carbon nanotubes

Abstract

Cyclic voltammograms of gold electrodes laden with carbon nanotubes covalently modified with various electron-withdrawing or donating moieties were measured. Carbon nanotubes modified with electron-donating bromophenyl groups showed a bandgap of 3.0 eV compared to 1.9 eV for unmodified purified tubes. Nitrophenyl substitution, which has a strong electron-withdrawing character yielded tubes with a bulk bandgap of 1.6 V. The bandgaps can be rationalized by considering the reactivity of the diazonium compounds and the relative populations of metallic and semiconducting tubes before and after modification. © 2009 The Electrochemical Society.