Low-Voltage Synergistic Thermal Conductivity of Wood-Based Graphene Composite Electrothermal Films

To address the limitations of conventional low-voltage electric heaters in achieving high saturation temperatures and rapid electrothermal response, this study presents a high-performance composite film of graphene nanoplatelets (GNP)/multiwalled carbon nanotubes (MWCNT) with a three-dimensional conductive network, fabricated via a layer-by-layer coating and hot-pressing process, utilizing pretreated natural wood veneer with enhanced hydroxyl group exposure as a sustainable substrate. Thermochemical and microstructural analyses reveal that a 1:1 GNP/MWCNT mass ratio optimizes the synergistic effect, where MWCNT bridges GNP layers to establish a continuous conductive pathway, reducing interfacial resistance and enhancing thermal transport. The resultant composite film with four coating layers (thickness: ~120 μm) exhibits exceptional electrical conductivity (2000 S·m⁻¹) and rapid Joule heating response (2 s), achieving a saturation temperature of 66.1°C–67.9°C under 4 V applied voltage. Cyclic stability tests confirm consistent performance over 3600 s at 4 V, with minimal temperature fluctuations. Furthermore, infrared thermography demonstrated uniform heat distribution (ΔT < 3°C across the surface) and superior heating rates (66°C in 40 s) compared to traditional resistance wire films. This scalable approach offers potential for eco-friendly, high-efficiency electrothermal materials in decorative applications.