Electrothermal vacuum sublimation drying of graphene aerogels for high-temperature synthesis.

Graphene aerogels have emerged as versatile material platforms for diverse critical applications, owing to their ultralight, highly porous architecture and attractive mechanical, electrical, and thermal properties. However, the precise and scalable synthesis of graphene aerogels remains a key challenge, particularly in developing efficient drying strategies that preserve their delicate nanostructures. Here, we devise an electrothermal vacuum sublimation drying method that integrates rapid Joule heating with vacuum-driven phase-transition engineering, achieving a 417-fold increase in drying rate while consuming only 0.6% of the electrical energy used by conventional freeze-drying. The high-temperature and low-pressure electrothermal vacuum sublimation drying environment enhances carbon-water reactions and accelerates the decomposition of oxygen-containing functional groups, thus preserving the porous structure and improving the high-temperature stability of graphene aerogels. Furthermore, the resulting graphene aerogels can serve as localized high-temperature resistive heaters, reaching temperatures exceeding 3000 K for rapid graphitization of mesocarbon microbeads, shortening the process from days to 20 seconds. Beyond drying, the versatility of electrothermal vacuum sublimation drying is further demonstrated through applications in chemicals and nanomaterials synthesis. This study presents a versatile strategy that integrates physical phase transitions with chemical transformations, enabling the precise and scalable fabrication of graphene aerogels and other advanced material systems.