Graphene-based (Gr-based) electrothermal heaters, due to their light weight, low electrical resistance, high thermal conductivity, and easy accessibility, have attracted widespread attention in the field of electrothermal heating. To achieve a high steady-state temperature in electrothermal heaters under low voltage, here we constructed a Gr-based film with low electrical resistance. Firstly, we employed non-toxic vitamin C to reduce silver nitrate for the in situ chemical deposition of silver nanoparticles (AgNPs) on the Gr surface. The SEM results confirmed that the AgNPs were uniformly deposited on the Gr surface. The synergistic interaction between AgNPs and Gr provided high-speed electrons transport paths for the film. On the other hand, we employed biodegradable lignocellulose fiber (LCF) as a dispersant and film-forming agent. The aromatic ring structure of LCF interacts with Gr via π-π interactions, aiding the dispersion of Gr in aqueous solutions. SEM results revealed that LCF permeated through the surfaces and interstices of the two-dimensional Gr sheets, providing mechanical support for the composite film. This approach enables the creation of freestanding Gr-AgNPs/LCF electrothermal composites. The resistivity and electrothermal results demonstrated that the obtained 20 wt% Gr-based composite film possessed low electrical resistance (5.4 Ω sq-1) and exhibited an outstanding saturated temperature of 214 °C under a very low input voltage of 7 V. The preparation method of this Gr-based composite film is simple, easy to operate, and environmentally friendly, providing a new reference for the preparation of eco-friendly and high-performance resistance heating electronics.
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