Construction of CuO/PPy heterojunction nanowire arrays on copper foam as integrated binder-free electrode material for high-performance supercapacitor

•The 3D CuO/PPy NAs on Cu foam was fabricated by anodizing and electropolymerization method.•A areal capacitance of 1080 mF cm−2 (675 F g−1) at 2 mA cm−2 was achieved in 3 M KOH electrolyte.•The potential window of the asymmetric supercapacitor (ASC) was extended up to 1.7 V.•The constructed ASC can provide an energy density of 0.93 mWh cm−2 at a power density of 1.71 mW cm−2.