Nanoporous Conductive Carbon Films via High‐Carbon‐Yield Carbonization of Poly(p‐phenylene benzobisoxazole) Nanofibers

High-carbon-yield precursors are crucial for producing stable carbon materials that retain porous architectures after high-temperature treatment. Here, we demonstrate that a rigid-rod polymer, poly(p-phenylene benzobisoxazole) (PBO) nanofiber networks yield nanoporous carbon films upon carbonization at 700°C-1000°C, achieving high structural integrity and specific surface area (279 m²/g). The high carbon yield of PBO preserves the interconnected nanofiber network and promotes the formation of graphitized carbon domains. A clear disorder-to-order transition with reduced heteroatom defects is observed at elevated temperatures. These structural evolutions enhance thermal conductivity from 27.2 to 63.2 W/m K and electrical conductivity to 2160 S/m, enabling rapid and stable Joule heating. The resulting nanoporous carbon films exhibit a high electromagnetic interference (EMI) shielding efficiency of 39.8 dB, primarily governed by multiple internal reflections and dielectric losses. This study highlights the significance of high-carbon-yield precursors for lightweight, porous, and conductive carbon films for efficient EMI shielding and thermal management.