Carbon nanotube film electrodes enabled by nanostructured biopolymers through aqueous processing

Abstract

Processing carbon nanotubes (CNTs) into conductive films via liquid-phase is highly attractive for the fabrication of electronic and electrochemical device components. However, conventional deposition methods usually suffer from several limitations, including environmental concerns, loss of intrinsic properties, and poor reproducibility. Nanostructured biopolymers (NBs), such as cellulose (CNCs) and chitin (ChNCs) nanocrystals, offer an environmentally friendly strategy for dispersing CNTs in water alternative to organic solvents, surfactants or chemical functionalization. In this work, we present the first direct comparison of conductive and electroactive films resulting from using CNCs and ChNCs as dispersing agents for both single-walled and multi-walled CNTs. The as-made aqueous dispersions are used as inks to fabricate CNT/NB films via spray coating, achieving excellent homogeneity, controllable film thickness, and sheet resistances mostly below 130 Ω □⁻¹. Furthermore, we demonstrate that post-deposition thermal treatment at 450 °C in an inert atmosphere effectively pyrolyzes the non-conductive NB matrix while increasing contacts between CNTs in the network, leading to enhanced electrical conductivities and electrochemically active surface areas. These findings highlight NBs as greener processing agents for the formulation of waterborne CNT inks and emphasize their relevance for the controlled and sustainable fabrication of conductive films and electrodes.