Multifunctional biocarbon/cellulose composites: Synchronizing superior EMI shielding, flame Retardancy and biofertilization via cradle-to-cradle strategy.

Current shielding technologies predominantly focus on performance optimization while neglecting fire safety considerations especially in construction building. To address the vulnerability of electromagnetic interference (EMI) shielding materials to accidental fires, we develop sustainable biocarbon/cellulose composites with integrated EMI shielding and flame-retardant capabilities. This approach employs porous biocarbon particles as functional units combined with three-dimensional cellulose networks through hydrogen bonding, van der Waals forces, and physical entanglements. The resulting composite exhibits exceptional electromagnetic interference shielding effectiveness (EMI SE) reaching up to 81.6 dB and superior flame resistance with a limiting oxygen index (LOI) greater than 37 %. Notably, the total heat release and total smoke production of the composite are only 0.4 MJ/m and 14 m, respectively, corresponding to reductions of 97.2 % and 98.7 % compared to traditional plastic sample. Significantly, the biocarbon/cellulose composite also offers substantially lower environmental impacts compared to petroleum-based plastics, with the potential for waste to serve as biofertilizer enhancing plant growth and facilitating carbon sequestration. This cradle-to-cradle paradigm contrasts fundamentally with conventional non-degradable petroleum-based polymers, establishing an environmentally friendly alternative for advanced material applications.