Heating-Rate-Induced Porous α-Fe2O3 with Controllable Pore Size and Crystallinity Grown on Graphene for Supercapacitors

Porous alpha-Fe2O3/graphene composites (S-PIGCs) have been synthesized by a simple hydrothermal method combined with a slow annealing route. The S-PIGCs as a supercapacitors electrode material exhibit an ultrahigh specific capacitance of 343.7 F g(-1) at a current density of 3 A g(-1), good rate capability, and excellent cycling stability. The enhanced electrochemical performances are attributed to the combined contribution from the optimally architecture of the porous alpha-Fe2O3, as a result of a slow annealing, and the extraordinary electrical conductivity of the graphene sheets.