High–performance 3D CuO/Cu flowers supercapacitor electrodes by femtosecond laser enhanced electrochemical anodization

Changing morphology and chemical compositions of electrode active sites is an effective approach to enhance the performance of supercapacitors. Herein, a novel method has been proposed to prepare 3D porous copper oxides electrodes of supercapacitors. CuO flowers were directly grown on copper foam by the combination of femtosecond laser processing and electrochemical anodization. A femtosecond laser was used to create micro/nanoprotrusions served as the precursors for the following anodization. During anodization, the morphology and performance of the electrodes were optimized by controlling current densities and anodization times. The grown CuO flowers acted as the active materials of binderless and additive free supercapacitor electrodes. Benefiting from the unique morphology, providing plentiful redox active sites and enabling electrolyte ion access easily, a high specific capacitance of 3348.57 mF cm⁻² at the current density of 1 mA cm⁻² was achieved. The specific capacitance of the electrode is superior to that of electrochemical anodization. The electrode exhibits excellent rate capacity (82.5%), good cycle ability (120%), and superior coulombic efficiency (97%) during 1400 cycles. In addition, the electrode also delivers a high energy density of 56.97 μWh cm⁻² at the power density of 175 μW cm⁻². These results indicate that this versatile combined fabrication process is suitable for improving the electrochemical performances of copper oxides–based 3D electrodes, which have promising applications in commercial devices.