▎ 摘　　要

Hydroxyl radicals ((OH)-O-center dot) generated from a UV/O-3 solution reaction is used to efficiently etch graphene oxide nanosheets under moderate conditions. Reduced holey graphene oxide is directly used as a supercapacitor electrode material and exhibits high specific capacitance (224 F g(-1) at a current density of 1 A g(-1)) and high volumetric capacitance (up to 206 F cm(-3)).