Wood-Inspired Compressible, Mesoporous, and Multifunctional Carbon Aerogel by a Dual-Activation Strategy from Cellulose

Natural materials often inspire various strategies in materials science, and these concepts have been extensively applied to enhance the compressibility of carbon aerogels (CAs). Herein, a novel combination of directed freeze casting and dual activation is adopted to prepare compressible and mesoporous CAs which imitate the vertical channel and porous structure of wood. The orderly growth of ice crystals generates vertical channels in cellulose that have a high strength-to-weight ratio, giving the material supercompressibility (up to 90% strain) and low density (3.8 mg cm–3). As sources of N and P, NH4H2PO4 decomposes into NH3 and H3PO4 which combined with a CO2 treatment create a mass of mesopores in the vertical channels. The optimized CA has a large specific surface area (1553 m2 g–1), a high mesoporous ratio (70.37%), and respective N and P contents of 4.29 and 3.05 atom %. This material has broad potential in supercapacitors, desalination, and elastomeric conductors. Consequently, the optimized CA has a high specific capacitance of 367 F g–1 at 1.0 A g–1. A capacitive deionization cell assembly shows a high desalination capacity of 26.4 mg g–1 (504 mg L–1 NaCl). Furthermore, a LED lamp connected to CAs can be lit in the same circuit.