Facile synthesis of bimodal nanoporous carbons by templating selective Swelling-induced mesoporous block copolymers

There is a strong need for simple and efficient strategies to produce nanoporous carbons with hierarchical porosities for a number of applications such as supercapacitors. Here we demonstrate the ease preparation of nanoporous carbons with both microscale and mesoscale porosities by infiltrating oligomeric phenol–formaldehyde resols into mesoporous block copolymer (BCP) templates followed by thermopolymerization and carbonization. The mesoporous polymeric templates are produced by an extremely simple and highly flexible selective swelling method which involves only the immersion of the BCP film into hot ethanol for a few hours and the subsequent air drying of the BCP films. The produced carbons exhibit mesoporous structures with thin pore walls containing micropores, implying a hierarchical porosity of the porous carbons. Such hierarchically porous carbons work as supercapacitors exhibiting a capacitance as high as 173 F/g at 1 A/g. Additionally, an excellent high-rate and steady capacitance of 165 F/g at 5 A/g is maintained after 10,000 cycles. The excellent performances are originated from the fast ion transport pathways and the low resistance of charge diffusion enabled by the hierarchical structures. This work suggests a new path to synthesize nanoporous carbons with hierarchical porosities which are expected to find more applications including but not limited to supercapacitors.