3D CuxCO-Cu nanostructures were synthesized through a simple chemical corrosion method and were employed as binder -free electrodes for supercapacitors. Owing to the direct growth of the active materials onto the Cu foam without any binders, and the 3D interconnected structure ensures a highly conductive network favorable for electron transfer, the as-prepared electrode exhibit a high specific capacitance of 111 mF cm (2) at 0.5 mA cm (2) and a better rate capability of 80 mF cm (2) at 10 mA cm (2). Besides, the Cu,O-COAC asymmetric supercapacitor can deliver a high energy density of 34.36 mu W h cm (2), thus showing great potential for supercapacitor applications. (C) 2016 Elsevier B.V. All rights reserved.