The facile conversion of iron foam into copper-coated 3D porous cobalt ferrite/iron foam for high-performance asymmetric hybrid supercapacitor

•3D porous CoFe2O4 is prepared with Fe foam as the sacrificing template.•Fe foam was coated with copper film via a simple galvanic displacement reaction.•Cu@Fe foam was converted into Cu@CoFe2O4/Fe via a hydrothermal route.•Cu film catalyzes the synthesis of CoFe2O4 while acts as the current collector.•Cu@CoFe2O4/Fe presents excellent electrochemical performance. [Display omitted] In this work, copper-coated CoFe2O4/iron foam (Cu@CoFe2O4/Fe) is synthesized with a facile method, including the growth of the copper film on the surface of iron foam via a displacement reaction between iron foam and Cu(II), and the subsequent partial conversion of the interior iron to CoFe2O4via a hydrothermal reaction by heating the copper-coated iron foam (Cu@Fe) in the aqueous solution of cobalt nitrate. Iron foam is used as the self-sacrificial template not only for the synthesis of cobalt ferrite foam but also the synthesis of the copper film. The high porosity of Cu@CoFe2O4/Fe facilitates the mass and charge transport at the solution/electrode interface, while the coating of the CoFe2O4 with copper film effectively hinders the volume expansion of CoFe2O4 and subsequently prevents the falling off of CoFe2O4 during the vigorous charging/discharging process, as evidenced by the high areal capacity, good rate capacity and extraordinary cycling stability of Cu@CoFe2O4/Fe.