Graphene oxide with tailored low thermal conductivity by defect engineering, for thermal insulation

The present study suggests a viable strategy for the development of next-generation nanomodified materials, exhibiting tunable intrinsic thermal management properties by adjustment of physicochemical aspects of graphene oxide (GO) dopants. Starting from a modified Hummers-based synthesis route, two complementary defect engineering strategies were investigated for suppressing thermal transport, namely lateral size control by mechanical treatment such as ultrasonication and defect introduction by oxygen plasma. The Raman ID/IG defect index was increased with both sonication duration and oxygen plasma exposure, confirming the progressive introduction of structural defects. Hybrid treatments yielded synergistic enhancements in the defect index, with values reaching 20% higher than the as-synthesized nanocarbon. Thermal conductivity, measured under the Transient Plane Source configuration exhibited plausible reductions in value, of ca. 26%, comparable with the value measured for an independent graphene oxide variant, stemming from oxidation of pristine graphene nanoplatelets. The finding demonstrates that chemical oxidation is equally effective to mechanical treatment for thermal transport suppression. While the two defect engineering pathways operate through distinct and complementary mechanisms, namely edge-related phonon scattering for mechanical treatment and basal-plane sp³ defect introduction for chemical treatment, their synergistic combination in the hybrid approach is envisioned to achieve further reductions in thermal conductivity.