Rapid Joule-Heating Preparation of GO/GNs Graphene-Based Composite Films for Thermal Management

Traditional metal heat sinks are limited by moderate thermal conductivity, high density, and poor flexibility, which restrict their use in compact and lightweight electronics. Graphene films offer high in-plane thermal conductivity, but rapid reduction of graphene oxide (GO) releases gases from oxygen-containing groups and can generate pores, interlayer damage, and poor film densification. Here, we report a precursor-design strategy that combines reduced graphene oxide nanosheets (GNs) with carboxylated cellulose nanofibers (CNFs). The composite films (GO/GNs-X) were prepared by blade coating, hot-press carbonization, and secondary Joule-heating graphitization. The combined precursor was designed to mitigate gas-release-induced damage and support carbon-network reconstruction during high-temperature treatment. The optimized GF, with a thickness of approximately 25 μm, reached an in-plane thermal conductivity of 950.5 ± 20 W m-1 K-1 and an electrical conductivity of 2.31 × 105 S m-1. At a comparable thickness, this thermal conductivity was 26.6% higher than that of an additive-free RGO-2600-ref film prepared without GNs/CNF modification. In LED heat-dissipation tests, the surface-centre temperature decreased from 83.7 to 40.4 °C. Because individual-additive controls were not included, the respective contributions of GNs and CNF could not be separated. These results establish combined precursor modification as a route to thin, lightweight graphene heat spreaders. Such films may be useful for thermal management in compact electronics, foldable devices, and aerospace systems.