Development of Green Lignin–MWCNTs Hybrids for Sustainable Conductive Materials

The increasing environmental impact of electronic waste has intensified the pursuit of sustainable materials for manufacturing green electronics. This study presents the development of lignin-based hybrids with multi-walled carbon nanotubes (MWCNTs) via an environmentally friendly ultrasonication process in aqueous medium. Two hybrid materials containing 10 and 20 wt% MWCNTs were synthesized and thoroughly characterized. DLS analysis revealed better dispersion and colloidal stability due to strong physicochemical interactions between lignin and MWCNTs, while SEM and TEM images confirmed a continuous lignin matrix embedding an interconnected MWCNT network. Raman spectroscopy indicated structural ordering within the hybrids. The electrical conductivity of the hybrids reached 2–5 S/cm as evaluated by four-point probe measurements, despite the high lignin content (80–90 wt%). Electrochemical analysis suggested significantly enhanced redox activity and electron transfer kinetics, with measured electroactive surface areas increasing up to 21-fold larger compared with the unmodified electrode. The synergy between lignin and MWCNTs enabled the formation of a conductive network, highlighting these hybrids as promising, cost-effective, and sustainable materials for conductive and electrochemical applications in next-generation green electronics.