Designing MOF-Cellulose Bio-Aerogels for Electromagnetic Management and Fire-Acoustic Safety

Lightweight multifunctional aerogels hold great promise in applications, e.g., electromagnetic microwave absorption, thermal insulation, and acoustic damping. However, conventional aerogels often suffer from limited functionalities, complicated manufacturing, and poor sustainability. Metal-organic frameworks (MOFs), with tunable porosity and abundant active sites, offer a compelling route to high-performance multifunctional aerogels, but it has remained a grand challenge to develop sustainable multifunctional MOF-based aerogels. Here, we report a sustainable multifunctional bio-aerogel (Ni-CCA) by integrating hierarchical scale-like topological Ni-MOF-NH₂ with cellulose through simple pretreatment using deep eutectic solvent followed by stepwise assembly-carbonization. The resulting aerogel features an ultralow density and a 3-dimensional layered porous structure. With 5 wt.% filler loading, Ni-CCA achieves a minimum reflection loss (RL_min) of -53.47 dB and an effective absorption bandwidth of 4.42 GHz, along with a radar cross-section suppression of 27.90 dB·m². Additionally, Ni-CCA shows enhanced flame retardancy (64.3% reduction in peak heat release), low thermal conductivity [33.3 mW/(m·K)] and improved acoustic damping (NRC of 0.31, 15 to 23 dB attenuation). The multifunctionalities of this bio-aerogel stem from its hierarchical architecture and synergistic loss mechanisms, offering a promising strategy for creating the next generation of lightweight multifunctional protective materials.