Hierarchical CuO nanorod arrays in situ generated on three-dimensional copper foam via cyclic voltammetry oxidation for high-performance supercapacitors

Abstract

Unique hierarchical cyclic voltammetry oxidation (CVO) Cu@CuO nanorod arrays were obtained by an in situ oxidation reaction with the combination of calcination and cyclic voltammetry oxidation strategies. The areal capacitance of this CVO Cu@CuO electrode reaches 1.674 F cm⁻² (594.27 F g⁻¹) at a current density of 2 mA cm⁻², which is significantly higher than those of Cu@Cu(OH)₂ (0.207 F cm⁻²) and Cu@CuO (1.307 F cm⁻²) electrodes. In addition, an excellent rate capacity (1.085 F cm⁻² at a current density of 30 mA cm⁻²) and remarkable cycling stability (96.45% after 4000 cycles) were observed. Additionally, the CVO Cu@CuO nanorod arrays can also be utilized as the positive electrode to manufacture asymmetric supercapacitor (ASC) devices, realizing a high cell voltage of 1.5 V and an outstanding energy density of up to 35.43 W h kg⁻¹ at a power density of 520.99 W kg⁻¹. The excellent electrochemical properties can be credited to the unique hierarchical structures. This work makes it attractive in that the CVO Cu@CuO can be utilized as a potential electrode material for supercapacitors.