Preparation, characterization and electrochemistry of viologen-functionalized carbon nanotubes in the casting films and layer-by-layer multilayers

Electroactive organic electrolyte of viologen was covalently attached on the multiwalled carbon nanotubes (MWNTs) via a diazonium coupling process to form viologen-functionalized nanotubes (MWNTs-PhV), which was then used as an alternative nanolayer to form layer-by-layer (LBL) multilayers with poly(sodium-p-styrenesulfonate) (PSS) at interfaces. Compositions and morphologies of the nanocomposites of MWNTs-PhV and the LBL multilayers were characterized by using thermogravimetric analysis, infrared and Raman spectra, X-ray photoelectron spectra as well as by scanning electron microscope and field emission transition electron microscope. The relative content of viologen in the nanocomposites was about 30% in weight. Cyclic voltammograms of the MWNTs-PhV nanocomposites in the casting film and LBL multilayers revealed a couple of redox wave in the potential range of −0.3–−0.7 V vs. Ag/AgCl, corresponding to the electron transfer process of MWNTs-PhV2+ ↔ MWNTs-PhV+.