Non-Equilibrium Carbothermal Shock Upcycling: Atomically Precise Synthesis of Tailored SiC Polytypes and Novel Hybrid Graphene from Complex Composites.

Abstract

The complex, heterogeneous nature of challenging precursors, as seen in end-of-life wind turbine blades, typically comprises glass or carbon fiber-reinforced polymer composites with polyvinyl chloride foam cores. This complexity poses a significant material synthesis challenge, particularly for achieving high-value recovery with precise structural control. A transformative one-step, ultrafast carbothermal shock (CTS) process is presented that selectively converts these intricate, unseparated composites into high-value SiC polytypes or novel graphene structures. Leveraging ultrafast Joule heating, CTS enables remarkable atomic-scale phase control, facilitating kinetic trapping of specific non-equilibrium structures such as metastable 6H-SiC and a unique hybrid AB-turbostratic graphene. This unique hybrid graphene combines the high charge carrier mobility of AB-stacked nanodomains with the enhanced mechanical interlocking of turbostratic nanodomains. This results in exceptional electrical conductivity (1791 S m^-1) and substantial mechanical reinforcement (+21.8%) in composites, significantly outperforming conventional reduced graphene oxide. Multiscale characterization and simulations elucidate the atomic-scale mechanisms driving this phase evolution and kinetic trapping. The study establishes a new paradigm for advanced materials synthesis from complex feedstocks, transforming critical waste into on-demand functional materials with compelling environmental benefits and dramatically lower operational costs. This sets the stage for sustainable material innovation and a circular economy.