▎ 摘　　要

Reduced graphene oxide hydrogels (rGOHs) with tunable surface functionalities were prepared through a hydrothermal treatment. The self-standing hydrogels were directly used as electrode materials without any binder or conducting agent in aqueous electrolyte. Electrochemical measurements show that the hydrogels can endure high potential up to 1.7 V in acid (H2SO4) and KI-additive (H2SO4+KI) electrolyte. With the introduction of extra pseudocapacitance through KI, rGOH possesses a high specific capacitance of 539 F g(-1), which is much larger than that (141 F g(-1)) in acid electrolyte. The energy density for rGOHs-based supercapacitor with can reach up to 54 Wh kg(-1) and the value can maintain at 28.8 Wh kg(-1) even a high power density of 8500 W kg(-1). Such a good supercapacitive performance can be attributed to the open porous and interconnected structure, together with surface functionalities.