Carbon aerogels based on regenerated silk proteins and graphene oxide for supercapacitors

Carbon aerogels based on regenerated silk proteins and graphene oxide (GO) were prepared by a flash freezing/lyophilization process followed by carbonization. Hydrophilic blocks of ampiphilic silk proteins showed strong interactions with the oxygen functional groups of GO through intermolecular hydrogen bonds, resulting in silk-protein-coated GO nanoplates. The silk-protein-coated GO nanoplates were assembled into 3D cryogels by the gelation of the silk proteins after a flash freezing/lyophilization process. The cryogels based on GO and silk proteins, which contained numerous nitrogen heteroatoms, were successfully transformed to carbon aerogels after crystallization by a methanol treatment. Consequently, the nitrogen-enriched carbon aerogels exhibited a high capacitance of 298 F/g because of significant contributions from the pseudocapacitive effects. A specific energy of 63 W h/kg, specific power of 20 kW/kg, and stable cycle life of over 5,000 cycles were achieved.