▎ 摘　　要

Steel rolling sludge containing high amounts of iron was recycled for the first time via a facile hydrothermal method and used as ferric ions source for CoFe2O4/graphene nanocomposite electrode. CoFe2O4 agglomeration is weakened by introducting graphene, which is crucial for improving efficient ions transport pathways in energy storage devices. The CoFe2O4/graphene complex exhibits a rough morphology and a porous nanostructure with a high specific surface area of 191.5 m(2) g (1). The material also shows excellent Faradaic redox reactions with high specific capacity of 166.5C g (1) and 127.0C g (1) at 0.5 and 10 A g (1), respectively, which are higher than that of simple, dense CoFe2O4 particles (121.6C g (1) at 0.5 A g (1)). Furthermore, the electrode demonstrates outstanding cycle stability with 79.3% capacitance retained after 5000 cycles. Hence, the proposed resource reuse strategy can be used to prepare CoFe2O4/graphene nanocomposites for supercapacitors. (C) 2017 Elsevier Ltd. All rights reserved.