Charge-Regulated Electrochemistry in Self-Standing Carbon Nanotube–Nanocellulose Hybrid Electrodes

Self-standing electroactive thin films enable direct interrogation of intrinsic structure-composition-property relationships without contributions from external current collectors. Here, we report a bioderived hybrid thin film composed of single-walled carbon nanotubes (SWCNTs) and TEMPO-oxidized cellulose nanofibers (TOCNFs) that functions simultaneously as a conductive scaffold and an electrochemically active sensing interface. The hybrid architecture integrates the hydrophobic, conductive SWCNTs with the hydrophilic, carboxyl-functionalized TOCNF network to form a mechanically robust, porous film with composition-tunable interfacial charge and electron transfer properties. By systematically varying the SWCNT:TOCNF ratio and electrolyte conditions, we elucidate how hybrid composition governs charge distribution, redox probe accessibility, and electron transfer kinetics. The optimized self-standing films exhibit reproducible, composition-dependent electrochemical behavior and enable electrostatic discrimination between oppositely charged redox species. These findings provide mechanistic insight into charge-regulated electrochemistry in carbon nanotube-nanocellulose hybrids and establish composition-controlled charge regulation as a design principle for self-supporting electroactive thin films.