Synthesis of Mirror-Like, Large-Grained Graphite Films Using Ni-Mo Alloy Melts

Graphite, known for its anisotropic physical properties, has widespread applications in thermal management, composites, and various other fields. Achieving high-quality artificial graphite crystals with large grain sizes and smooth textures has been a long-standing challenge. We report the synthesis of mirror-like, large-grained graphite films with controllable dimensions, achieved by using flat Ni-Mo alloy melts as catalysts. In our method, after the formation of the graphite film, we deliberately evaporated a significant portion of Ni, producing a porous metallic substrate. This step weakens the substrate-graphite film interaction before cooling down to room temperature, resulting in graphite films with only a few nano kinks and a mirror-like appearance. The synthesized films are 100% AB-stacked with millimeter-sized grains, much larger than the multi-micron grain size of highly oriented pyrolytic graphite and rivaled in size only by a small percentage of natural graphite. The films demonstrate an electrical conductivity of 5.59 × 10⁶ S/m at 4 K and 7.75 × 10⁵ S/m at 300 K. Tensile testing of macroscale samples revealed an average Young's modulus of 969 ± 69 GPa and an average fracture strength of 1.29 ± 0.203 GPa, which are, to the best of our knowledge, the highest values reported for macroscale artificial graphite materials. Our method provides a promising approach for synthesizing high-quality graphite films with exceptional properties, opening up new avenues for their potential applications in various fields.