The development of advanced oxidation processes to generate reactive oxygen species (ROS) has been one of the most important and great challenging goals in environmental catalysis field. Herein, a representative of persistent free radicals (PFRs), activated carbon fibers (ACFs), was innovatively employed to construct a novel and outstanding catalytic system, Cit-Fe@ACFs/AA/H2O2, in which PFRs act as an electron sink to release electrons to Cit-Fe ("discharging"), thus accelerating the reaction rate-determining step of Cit-Fe-III to Cit-Fe-II. Meanwhile, ascorbic acid (AA) serves as an electron donor provides electrons to ACFs to supply the consumed PFRs ("charging"). Previously, AA was mainly reported to be a ROS scavenger instead. Remarkably, in our system, the PFRs coupled with AA enabled unblocked electron transfer, strongly improving the generation of ROS ((OH)-O-center dot), allowing for an extreme rate enhancement in oxidative decomposition of organic contaminants by hundreds of times compared with that of the sole Cit-Fe/H2O2 system. (C) 2016 Elsevier B.V. All rights reserved.