Functionalized Nanocellulose/Multiwalled Carbon Nanotube Composites for Electrochemical Applications

Abstract

Four different types of crystalline and fibrillar nanocellulosic materials with different functional groups (sulfate, carboxylate, amino-silane) are produced and used to disperse commercial multiwalled carbon nanotubes (MWCNT). Aqueous nanocellulose/MWCNT dispersions are drop-cast on tetrahedral amorphous carbon (ta-C) substrates to obtain highly stable composite electrodes. Their electrochemical properties are studied using cyclic voltammetry (CV) measurements with Ru(NH3)62+/3+, IrCl62-/3- redox probes, in electrolytes of different ionic strengths. All studied nanocellulose/MWCNT composites show excellent stability over a wide potential range (-0.6 to +1 V) in different electrolytes. Highly anionic and more porous fibrillar nanocellulosic composites indicate strong electrostatic and physical enrichment of cationic Ru(NH3)62+/3+ in lower-ionic-strength electrolytes, while lesser anionic and denser crystalline nanocellulosic composites show no such effects. This study provides essential insights into developing tailorable nanocellulose/carbon nanomaterial hybrid platforms for different electrochemical applications, by altering the constituent nanocellulosic material properties.