Facile and scalable synthesis of hierarchically porous graphene architecture for hydrogen storage and high-rate supercapacitors

Porous graphene materials have been developed for many energy applications. However, a facile and scalable synthetic approach is still a challenge. Herein, we prepare graphene-based carbons with hierarchically porous structures via a simple steam activation of oxygen-functionalized graphene nanosheets. The as-prepared carbons show interconnected micro-meso-macroporous structures, high specific surface areas up to 1238 m2 g−1 and ultra-large pore volumes up to 4.28 cm3 g−1. The highest hydrogen storage on the carbon sorbents is found to be 1.47 wt% at 77 K and 1 bar. As electrode materials for supercapacitor, one of the carbons delivers a specific capacitance of 121 F g−1 at 0.5 A g−1 with 85% retention at 20 A g−1. The enhanced surface area, unique porous structure combined with the inherent properties of graphene are responsible for the excellent performances in hydrogen storage and high-rate supercapacitors.