Gas Altered Hierarchical Porous Graphene Aerogel with High Energy Density

A hierarchical porous graphene aerogel (HP-GA) with hand tearing bread like macro-morphology is achieved through hydrothermal treatment a mix suspension of manganese dioxide (MnO 2 ) and hydrogen chloride (HCl) containing graphite oxide (H-GO) before freeze drying. The chlorine gas (Cl 2 ) as a result of the reaction of HCl and MnO 2 is responsible for the formation of the hierarchical porous microstructure and hand tearing bread like macro-morphology. When used as the active electrode material in supercapacitors, the HP-GA exhibits a large specific capacitance of 284 F g -1 at 1 A g -1 and ultrahigh energy density of 10 Wh kg -1 at 250 W kg −1 in aqueous electrolyte. This work provides a versitile, simple and easy-to-controlled way to alter the microstructure and macromorphology of graphene-based areogels that have promissing applications in many areas including adsorption, energy storage, heat insulation, acoustical insulation and intelligent sensing.