Interfacial Characterization of Single- and Multi-Walled CNT-Doped Chitosan Scaffolds under Two Flow Conditions

Abstract

This work describes electrochemical interfacial mechanisms under different flow conditions for glassy carbon scaffold electrodes (GCEs) modified with single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) dispersed within a chitosan (Chit) polymer. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize and assess the interfacial response. High-resolution techniques also revealed that carbon nanotubes dispersed within a Chit solution provide homogeneous distribution on glassy carbon substrates. The MWCNT-Chit scaffold CV response exhibited a six-fold increase in the redox peak currents (Ipa = 381 μA versus 55 μA for bare GCE). EIS was performed at different polarization potentials based on the results of the anodic peak potential, as measured by CV, in order to elucidate and characterize the charge and mass transfer mechanisms of the nanostructure-modified electrode surfaces so that the influence of flow conditions and redox potential on its performance, could be determined. The selected potentials were: open circuit potential (OCP), 0.2 V, 0.3 V, and 0.4 V. A combination of kinetic and diffusion processes resulted when Electrical analog element analysis was used to correlate the interfacial mechanisms at different flow and bias potential conditions. The EIS experiments demonstrated that Bode diagrams could be used to characterize the porous homogenous formation of layers in the scaffolds and provided new perspectives for those applications requiring flow-through conditions.